Very simple: Lewis is making sure to be in a win-win situation no matter the result; he,s almost making sure that people won't bug him off to come in the ring again and if they are willing to lay down 100 millions, well they are the morons and no matter what the issue of the fight, for 100 millions, he's clearly the winner.
One thing for sure; except PERHAPS for an eccentric billionaire, no serious promoter will ever shell that amount of money because there would then be no profits to be made at all (or way too little for the risks involved), especially because it doesn't include Vitali/Wlad's purse plus the other fees involved in the fight.