no, the whole thing wasn't a big con.
If it was a big con, they'd have found some nonentity for him to clobber- someone who looked like he'd never worn boxing gloves in his life and worked in a kebab shop.
if it was all a big con, Kel Brook would have been ushered into the ring at the end of the fight for the confrontation.
Hearn would have had a well rehearsed script ready to whip up interest in his next money-making quest.
oh, wait a minute, yes it was all a big con