I mean, forget about this specific Twister-laden example for a minute, is there ever another situation where you'd actually do a decklist check when one guy says, "Look, here's my lock, yet Opponent isn't doing anything but drawing cards, I want to go to game 3", and Opponent says, "I'm waiting until I draw my answer or he actually kills me, no dice" to see if this putative answer is in fact in the deck? Does it really make a difference whether or not the game has 20 minutes left, 10 minutes, 5 minutes? 5 turns? Because honestly, if someone's trying to win on the assumption that I'm going to scoop to their version of inevitability, that's bogus. And if they're going to look to the judge to see if I'm being a prick in claiming I've got an answer to their 'non-kill condition' when I don't, that's just as bad as sitting on the clock, isn't it?
So if my sole remaining win condition is Dark Confidant, but I fear to play it because of life loss is it considering stalling if I keep defending and passing the turn with Dark Confidant sitting dead in my hand?
As I've already stated, no, you're not required to concede. Even if you have nothing you can do, you're not required to concede. I never once said anything to the effect that you are required to concede, so would greatly appreciate it if people dropped this line of questioning (as this is now the second time I'm covering it). You don't have to scoop, you don't have to play a Dark Confidant that might kill you. Whether you have some answer you can draw or not, you can still sit there and wait for your opponent to kill you.
What you cannot do is waste time in the process. Spending a while after every card you draw "thinking" (some people believe, erroneously, that they're entitled to a set amount of time each turn) to kill the clock is definitely stalling. Actually thinking is perfectly fine and not stalling (if excessive it could be slow play, though). Even pretending to think in order to bluff (make your opponent think you have something when you're really holding lands) can be acceptable. But doing nothing to waste time is definitely not. And before anyone tries to suggest it, wasting time "thinking" while claiming you're just doing it to bluff your opponent out doesn't work either (I've seen this more than once). What matters is the reason you're actually doing it, not whatever you might want to claim is the reason.
To reiterate, one last time, you are never required to concede, you're not required to play something. You can always just sit there passing over and over waiting for your opponent to kill you, whether you might have an out or not.
I very much hope this clears it all up, and any further posts in this thread questioning being required to concede or play something that might harm you will be deleted.