I don't think that this has anything to do with race, but just the individual personallity of each person. Saying that Vince should feel different of MVP because he's been to jail and has had his personality change because of it doesn't mean that MVP can get away with certain things that other can. Should McMahon keep it in the back of his mind, maybe, but many other people have been through tough times and when having a job you must leave all personal thing aside and do your job.
Same with Carlito's lazyness, if it has to do with race or not. Riaku says that
As a puertorican, I can assume that Carlito's problems are in fact laziness. His dad owns a company. That means he has secured work. We are lazy people by nature.
so i am unsure if it has to do with his race, but Carlito is infact very lazy. Vince shouldn't change whether or not he should promote or fire a wrestler just because his race or background says that they are lazy. If a wrestler is lazy, he should be fired, and that's what happend. And I personally don't want to see a lazy wrestler, whether or not he is a certain race. Entertainment is entertainment and Carlito just ins't entertaining.
So if Shelton and Carlito are seen as lazy, whether it has to do with their race or not, it shouldn't matter. If McMahon thinks they look sloth, then most people will probably think the same way. I personally think both of the wrestlers look boring in the ring, and maybe McMahon feels the same, as well as MVP. I also feel the same for many other white wrestlers, Mike Knox, David Hart Smith, Dibiase and Drew McIntyre, so this isn't a race issue.
So I don't think anything McMahon has done has been because of race but what he feels the wrestlers in ring performance is like, which all 3 of these people IMO lack good in ring skills.