1. I think the primary reason for this is to drive Haye crazy, threatening to take away both of Haye's potential opponents (himself and Chisora) in one shot.

2. He fought the whole fight one-handed with a shoulder injury and some people thought it was close (if 8-4 is close) and that he's gotten old, so I think he'd like to try to prove otherwise with both hands against the same guy.

3. And it's not like there's any other great and deserving opponent out there in this weak-ass division.