"no way you gonna break down the posture of some of boys in UFC, if not they're wrestling base, the strength of the athletes alone makes the move too risky. You'll just get passed. "
What are you talking about? For the guard position, it's VERY common that the top guy has his face in the other guy's chest, which is a good opportunity for this move.
"If the triangle fails the only other subs the guy on the bottom can go for are the armbar or the omaplata, which are really low percentage moves from that position. "
A guy that's good with the triangle and perhaps also those other 2 moves, will be able to flow between all those moves and NOT get his guard passed. Actually, when the triangle fails, you don't necessarely have to go to another submission - you can just go back to your guard.
Honestly, I think that the reason is mostly that this move isn't taught widely enough and isn't a part of that many guys' strategy. I DON'T think it's that risky. Tell me what you would do instead, then? Just lie there and do nothing except throw the occasional weak punch? And hope that the referee stands you up later?
If you are going to be ACTIVE from the bottom of the guard and try ANYTHING instead of just stalling, this push-arm-out triangle setup is, in my opinion, a great move. I use the move all the time in submission grappling and I admit that I have little MMA experience. But I still see that this very move is one of the most commonly used guard attacks from the best "guard submitters" in todays MMA, like Nogueira and Jeremy Horn.
If I'm not mistaken, Eddie Bravo is basing his MMA guard program on the danger of this submission setup, f.ex. from his various rubber guard variations.
ttt for input from someone who is not just "guessing". He, he, unlike me and probably some of the guys on this thread :)