I think it's possible that that's one reason they've never gone there. FFVII does have some far more blatant acts of terrorism than other FF titles tend to.

But do I think it's a valid reason not to do it? Not really. It's been 11 years already. We need to move on from the idea that displaying acts of terrorism, even when it's the heroes doing it, in artistic works is a no no because 9/11. It stifles perfectly legitimate social and political commentary and allegory and I'll have no part of it.

But then, I've never believed that "because it will offend someone" is a valid reason to not do something if you think that thing has merit.