There's been a lot of hay made over whether Anderson Silva was "disrespectful" of Chris Weidman. I've argued, and I think pretty well, that, yeah, that Silva disrespected Weidman but as an intentional ploy. That his hands down wasn't so much a sign of arrogance, but an attempt to drawn Weidman into a striking match where Silva thought he'd have the advantage. But, without doubt, mocking your opponent openly is pretty disrespectful and it isn't the first time that Silva has done it.
However, MMA's rules are not particularly well enforced. Unknown to almost everyone, including, it appears, both MMA referees and the president of the UFC, is a rule that says, using abusive language in the fenced ring or fighting area is a foul.
I don't know what Silva said. Vitor Belfort didn't like it, but he didn't specify and I don't speak Portuguese. I do, however, speak English and a bunch of fighters use abusive language in the cage. I'm lookin' at you, Diaz brothers. They do it openly. Just watch their fights and even though you can't see them, it doesn't take that much lip reading to see them calling their opponents pussies, bitches, punks, faggots and various other swear words, like fuck, that are generally regarded as abusive. I don't know if Silva used abusive language - though it certainly looked like he did - but I do know that MMA . . . ignores it's own rules in this regard with great regularity.
More importantly than the question of whether or not Silva was disrespectful of Weidman, there's the issue of whether his behavior in that fight, and fights past, qualifies as a foul. I'm pretty sure that could be determined.
For my own part, I don't really care if fighters swear at each other. I find it slightly distasteful but I don't think it's a big deal. However, what I hate is when rules are enforced selectively and we have the idiocy of seeing the president of the biggest MMA organization in the world pretending he doesn't know what "respect" is in the context of martial arts. If there's a rule, enforce it. If you don't want it to be a rule, take it out. While you're at it, allow knee strikes to the heads of downed opponents. That'll also clear up a bunch of messes and be awesome.