Poppa, bodybuilding has been around for at least 100 years. I think that if it hasn't went mainstream by now it ain't gonna happen.
Mainstream? No, prolly not. But I still see potential in the rap industry.
Urban culture recognizes and respects physical accomplishment. Being a big muscular man, one of the "big dawgs", gives you "street cred" and raises you to a higher level of social status. Since Ronnie is bigger than anyone else, African American, and Christian, it seems reasonable that he would connect well with rap fans.
I suppose the only problems would be that he's a cop and oils up to pose on a stage in trunks. Doesn't bother me, but I can see how others would be put off.
At least that's my understanding.