I really have trouble blaming Activision for this one. From this article, it sounds like Troika was biting off way more than they could chew. Activision figured out that these guys weren't going to ever get the game done without a hard core deadline so they gave them six months to wrap it up.
If it were six weeks, yeah, that's just not feasible. But if you've been working on a game for three years and still aren't close to done, there's a big problem and I don't think it's the publisher's problem. Somebody at Troika was having problems saying "no" and it killed them.