As for others advocating extreme uses of force here these days, I agree with you that we should not go overboard. I do not, however, agree in the least with any pretended moral equivalence between those shouting that way in their passion right now, and either the people who attacked us on Tuesday or the ideology they believed in.
There remains a moral chasm between advising one's government to use extreme force after one's country has been attacked, and taking such matters into one's own hands, aggressively. I trust our system and leadership to filter out the noise of such extreme calls; that is just what states are meant to do. Those who act on their own lack the restraints that come with responsibility.
The anger people in the US feel right now is wholly justified, and is the energy behind justice. But like all passions, it must be regulated, channeled, and aimed by reasoning and responsible men. I am sure those voicing such attitudes will be governed by the more moderate actions our leadership will soon take.
It is also worth keeping in mind, however, the danger involved in the power of modern nation states. As a wise man who taught me much history once put it (John Mearsheimer), modern nation states are tremendously powerful killing machines, and they are not as easy to switch off as they are to switch on. That power must be handled with great care. So far as warning about that was all you meant, I quite agree with the sentiment.
I simply deny that morally speaking, those advocating extreme measures of retaliation today are on a par with the men who did this on Tuesday. Their advice is extreme and should not be taken. But they have offered it as advice; the men who crashed into the towers offered nothing and brooked no review of their murderous passions. That is not a trivial difference. The passions of mankind are always with us; they are in human nature. How they are governed makes the difference between civilization and its absence.
Calling for the killing of Americans, will be in effect a crime. And rightly so. Morally speaking, so also will the calling for the killing of Arabs and Muslims. Its just that the latter may be a safer crime.