Trying something stupid and going out on the canvas would be worse than ****. Haye clearly wanted to survive the full 12 to say he wasn't knocked out.
Quick reflexes require stamina and we all know Haye doesn't have the best stamina out there. He would need to be active, move and use his reflexes which will eventually wear him down.
Haye's got great footwork and headmovement everything that's needed to land a punch on Tysons face. Tyson's got dropped by two guys who where much lighter punches then haye and they didn't got half the footwork that david does.