I don’t see him as a conservative of any stripe. There are moral questions that the pragmatists always leave unanswered. Pragmatists, as I see it, almost lost both world wars for us.
I'm not sure I understand your historical point of view:
America's involvement in the first world war was of questionable national interest. The freedom of the seas and the ability to trade with European nations was as much compromised by the British surface Navy as it was by German submarines yet it was the submarine warfare which disturbed Americans.
Of course, there was the Zimmerman telegram which was certainly a causus belli but which many historians now believe did not actually motivate American policymakers to enter the war. In any event, there is a significant question about whether it would have been better for the Germans to have won that war in view of the terrible consequences which ensued. After all, there is some likelihood that the result of a German victory would have been similar to the German victory in the Franco-Prussian war rather than the travesty of the Versailles treaty.
As to World War II, I do not believe that there was any strong or effective political force on either side of the aisle that would have gotten us into the war sooner than Pearl Harbor. Pearl Harbor swept all objections aside. We must remember, however, that there was little knowledge of Nazi atrocities early on in the war. So I'm not sure a moral dimension comes into play in the actual historic circumstances. In retrospect, we think of World War II as the good war-and it was-but I'm not sure our motives were "moral" in the sense that we were going to make the world safe for Jews or other oppressed peoples at the time rather I think they were motivated by an instinct to survive. One questions whether it was more moral to fight the Nazis or the Soviets but I leave that for another day.
I do not deny either the power or the righteousness of the moral factor I just do not want to see realism swept aside.