I am not homophobic, but I, too, would suggest gay MMA competitors keep their sexuality to themselves. In a sport where two men essentially mimic sexual copulation whenever they're on the ground, which tends to be often, I can understand a straight fighter wanting to keep the battle on the feet.
And this would apply especially so in the gym where two fellas might be rolling around and in each other's "guard" (missionary position, to be frank) for hours on end, wearing what amounts to an almost Speedo-type suit.
Two hetero dudes can't be all too thrilled about doing this, to say nothing of when a pussy fan knows his opponent/training partner likes the cocko.