I realy don't think that's the problem.
I really think that no matter what, 25-33% of the electorate is 'terminally lib,' and that goes if 9-11 victimized 6,000, 9,000, 12,000 or 15,000. Their minds just filter and register things a certain (odd) way. Their reaction is superficially the same.
I think, similarly, that 25-33% of the electorate is 'terminally conservative,' and react to things also according to their world view.
The balance, the middle 34-50%, has no particularly strong opinions either way. I don't think that they would be reacting much differently if 6,000 people were killed om 9-11, or 12,000. Some will gravitate to the right, others to the left, others will be terminally 'open minded,' which is to say 'empty headed.'
None of this really has much to do with a body count. People belive what they believe. That's all.
Given that so many voters are numbskulls (and my life depends on their 'wisdom'), I'm beginning to like Heinlein's Starship Trooper notion that only people who have done military (or equivalent) service of some kind are qualified to be citizens and to vote to choose a government.
Yah, I think you're right. But how, then, in WW II, did the country get almost 98% of the people united? I mean, look at the list of HOLLYWOOD people who VOLUNTEERED!! (Borgnine, Holden, Bronson, Stewart, Savalas, Curtis . . . . on and on!) Even elite execs resigned positions and joined up.