Harrison is finished - if he was any way serious he would have had a fight before now (I haven't heard of one) and this would be an 8 rounder against someone half decent.
He's getting too old and I think he's trying to claw back some dignity, but he's not going to get it.
The chances are he'll come back to the UK and fight Sprott, Williams or the other brawler who's name escapes me, or Warren may be setting him up for a fall against Haye.
He'd be good cannon fodder for Haye, and would really get the general public buzzing about Haye in the UK if Haye beat him, which he would.
The only way I'm wrong is if he finally stops blinking when his opponent is throwing a punch! It may mean that he's grown some balls and is serious about winning.