First, I don't think I've ever seen Stephens classified as a "fire-eater" until now. Your attribution of beliefs to the "fire-eaters" is also inconsistent with a good ammount of their literature and commentary. Consider the following from perhaps the greatest of the "fire-eaters" and indisputably their leader in congress. He said it was economics that led him to conclude secession's inevitability, not some concept of racial equality allegedly promoted by Lincoln.
"You suppose that numbers constitute the strength of government in this day. I tell you that it is not blood; it is the military chest; it is the almighty dollar. When you have lost your market; when your operatives are turned out; when your capitalists are broken, will you go to direct taxation? Burn down a factory that yields ten, fifteen, twenty, twenty-five thousand dollars a year to its owner and he goes to the wall. Dismiss the operatives, stop the motion of his machinery, and he is as thoroughly broken as if his factory were burnt; for the time he is bankrupt. These are matters for your consideration. I know that you do not regard us as in earnest. I would save this Union if I could; but it is my deliberate impression that it cannot now be done....
Your irrepressible conflict is predicated upon the supposition that this is a consolidated Government; that there are no States; that there is a national Government, as they call it; that the people who live between the two oceans and between the Gulf and the lakes are one people; that the boundaries of Massachusetts have, by some hocus pocus, been extending themselves until they embrace all the remainder of the Union; and that we are one people, have a national Government, and are under the control of "the Massachusetts school of politics," as the Senator from New York said he was. This is the fatal error." - Sen. Louis T. Wigfall, December 1860
Walt
One reason for the fire-eaters' success was that they didn't simply parrot one line of argument. Some stressed slavery and race, while others downplayed them -- especially when the hope of winning English support was still alive -- in favor of economic or constitutional arguments or state sovereignty or Southern nationalism.
We are justified in viewing slavery and the anxieties surrounding its expansion or extinction as the major factors in the coming of war, because other sectional conflicts in American were generally resolved peacefully through the political process, but that doesn't mean slavery was the only topic of conversation or that there weren't other questions at issue. Racial politics would grow more pronounced after the war and the abolition of slavery, once the chains of bondage had been broken and new means of segregation were sought. In the antebellum period race didn't always have to be dealt with so directly. The issue of race was subjected or ordered or contained by the institution of slavery, and slavery and race were an important part of other ideas and watchwords of the time. That's not to say that slavery or race was the key to everything or that people were being deceptive or insincere, or that they didn't pursue their own goals and projects which they understood differently from us, just that one can't wholly dismiss slavery in discussions of the era.
At the time of your quote, Wigfall saluted the new prosperous King Cotton, and spoke of economic obstacles that the North put in the way of Southern economic development. In the same period he talked on several occasions about a state's right to leave the union for any reason or no reason. He also spoke of secret abolitionist societies allegedly stirring up trouble in Texas. He refered to the Republicans -- always the "Black Republicans" -- as a party of the "non-slaveholding states," whose principles were offensive and dangerous to the slaveholding states. If he said North and South or agricultural and industrial one might claim that slavery wasn't on his mind, but to frame the dissention as being one between slaveholding and non-slaveholding states, suggests that he wasn't indifferent or unconcerned about slavery. Some weeks later, in a clash with Stephen Douglas he discursed on colonial history and slavery among the biblical Hebrews, and the biblical support for slavery.
Latter-day Rockwellite free marketeers want to keep secessionist agitation against the tariff and throw away the even more passionate anger at the violations of the Fugitive Slave Law and the demand for still stricter enforcement of slavery. But that can't be done cleanly. The same people were passionate about both questions at the same time and regarded the refusal to return runaways as every bit as much a theft as wholly Constitutional protective tariffs. Even if one gives Wigfall the benefit of the benefit of the doubt, that subjectively slavery wasn't important to him personally -- which is unlikely -- there's still the objective question of just why secession and war came at that moment and not any other time. And those who reduce the Republican belief in Union to the Whig economic program or a scheme for enrichment, surely can't ignore the material interests and conception of property that would underlie and be promoted by the new Confederacy.
If you can argue that subjectively Wigfall had no liking for slavery -- there's no evidence for that -- still, slavery would be the base of the new country he envisioned. Wigfall's desire to create a new country, a powerful new force freed from Northern interference was strongly, overwhelmingly emotional and deeply felt. If he would have been willing to give up slavery, or if he differed in any regard from his fellow militants on the subject, if he would have been any gentler to gradual compensated emancipation than to any other obstacle in the progress of the new cotton empire, he could have given some indication at some time, and so far as I can see he did not.
Our views of the causes of wars tend to be idealistic and rational: our own side fights for ideals, the other for rational calculations of gain. But in fact, emotional and "irrational" factors can be very important. That's certainly true of the Civil War. The 1850s and 1860s saw passions take over from rational factors. Of course there were roughly rational disputes and much idealism, but also pride, anger, arrogance, rage, vengeance and other emotions. Wigfall's taunt to the North, "Your flag has been insulted; redress it, if you will dare. You have submitted to it for two months, and you will submit to it forever," is a pretty good indication of the mentality, or rather emotionality, that produced the war. It's also a good indication of why all our rationalistic arguments and moralistic interpretations don't get at the real atmosphere of the Civil War era.
Were Wigfall truly a leader in Congress, there would have been much more written about him by now. He certainly spoke often in the last pre-Sumter session of the Senate, but he was only in Washington for less than two years. Most of the existing record suggests that Wigfall was too emotional and erratic to play much of a role in government. If you find his ideas palatable today, it may be because his role at the time was rather peripheral and his paper trail more limited than that of his associates.