Sadly enough, it all has to do with marketing. White guys on the covers of BB magazines sell more issues-likely because the BB target market is young white males. After years of Haney being the IFBB posterchild, old J. Weider probably wanted a white guy(Dorian) to win for a change. I'd bet $$$ after Ronnie breaks Arnold's record, the new Mr O will be caucasion again. I doubt it will last though. Black dudes have naturally higher androgen levels and superior genetics as a result of selective mating back in the days of slavery. Whitey wanted strong hard working super slaves, so they deliberately mated the naturally bigger, stronger ones for a few generations-which is likely why blacks dominate in almost every pro sport. Whitey just can't hang in most cases.
In pro BB, a sport where genetics reign supreme, the brothers won't be able to be denied a top spot for too long(prolly just long enough to get an increase in M&F's subscribers?).
Now all we need is a heated hockey rink, and the brothers will fuck up whitey in that sport too. I doubt they'll ever dominate in swimming though. They'll probably never be president of the US either. Who'd want that job anyway?