There are probably a few things that decrease the changes of McGregor getting an unlikely win/ KO, e.g. the weight they fight at, the gloves used (size and type), the size of the ring, the choice of referee, when they fight (the sooner the better for Floyd) etc.
I'm pretty sure Mayweather would have had the final say on all of them.
Ultimately, you're right in the sense that it is a boxing match and boxing skill will be the biggest factor. But any little advantage he can get, you can bet Mayweather has covered it off.