Asking someone to wear a suit isn't homophobic. Reinforcing gender stereotypes maybe, but homophobic no.
People have to conform to dress codes all the time, especially if they are being paid. Someone who is a list status can make certain demands. This guy not so much. He needed the BET awards more than they needed him and I guess he forgot that.
Even A listers have to follow dress codes and have their outfits approved from time to time. He made the issue bigger than it was.