They could limit the rules to only allow punches with no clinching (ie, boxing with mma gloves) and Floyd would still get outclassed by the majority of the roster.
The simplest difference in boxing gloves vs open finger gloves completely changes everything. Keeping your hands close to your head in a boxing/kickboxing pillow defense stance is a death sentence in MMA against a good striker.
Go watch fighters like Mcgregor, Till, Gustafsson, Machida, Thompson, Stipe, ect ect. That wide open hand style is what elite bare knuckle striking looks like. Catching, parrying, moving, ect is far more crucial and easier with open hands. Distance is different, ect.
Floyd doesn't fare well, with all due respect.