I don't care about it representing that one second of screen time, I care about it being a tribute to Heath Ledger and the character he brought to life. So it being accurate to what he actually looked like in reality is what I find important, more then the expression he held for one second on screen. If I'd wanted that, I would have sent Adam a screen cap of that expression, and it would have been better then the Hot Toys sculpt. But I sent him a specific picture, which he accurately sculpted the expression from.
The eyes on this sculpt, I think, are quite mean, the way Heath was able to make his eyes look on screen. It doesn't pick up as well in photo's, just like the incredible detail of the sculpt itself doesn't. But it looks like the character of the Joker, with that same, cold indifference in the face.