A player would not be penalized for using it unless he used it in a way that was unsportsmanlike conduct.
I'm not sure I agree with that. You tell me, you've seen the tape, did Mr. Gray from Aledo use the throat slash in a way that was USC? I think he did, but it was pretty quick. He also wasn't facing any of the opposing players that I could see. Should it have been penalized? Well, I think so, but if you use your measuring stick, maybe not.
I think it's something that we simply tell players Don't do these things: alter stride, draw attention, ... And if they do one of those things, it's a foul.