If I was David Haye, I'd admit to using make-up to fake the cut. That would make me a coward and a sneak, but at least I would a appear to be a coward and a sneak with some brains.
The alternative would be that I was sparring without head-gear (guessing, as it is pretty hard for two guys to clash heads like that with head gear on) in my last session before a major fight. That would make me, and the people around me, look like a truck load of stupid mothers.