sorry about the spelling Quandram - I was too lazy to go back to the original post
if there are some really tiny stacks and you have 15BB, then that would incline you more towards a fold than otherwise. As you say it does depend somewhat on your objectives. One other point worth mentioning here is that presumably the transition from 21 players to 20 means that you will go from 3 tables of 7 to 2 tables of 10. That change is important as you have 8 hands between blinds rather than 5. The fact that you're heads up versus a very aggressive player, in a battle of the blinds, certainly justifies your suspicion that he was trying to bluff you off your chips.
I think it is definitely a +EV move in terms of tournament chips. The question largely revolves around how prepared you are to risk elimination versus win a decent prize. The likely structure would mean that this hand could make a big difference to your chances. My own attitude here would be that there is little difference between finishing 20th and finishing 14th or so - I'd want to be pushing to get into the top 6 or so or at least die trying! If, as you say, there were several microstacks then with 15BB in chips I might wait - as you are effectively now betting the 20th prize that one (or more) of them is eliminated before you act. I'd want 3 or more stacks with less than 3 BB to be confident in that regard though.
With the extra information you've given now, I'd say it is a pretty tough decision. Certainly not a clear fold IMO, but now not quite a clear call either. On balance I think (assuming there are several micro-stacks) I'd be more inclined to fold. No doubt music to muse's ears
But if those micro-stacks aren't there, then I'm calling
