I disagree, TBH. I think it's adequately covered as generic dangerous play.
Pre binding is something you see in nearly every game and I can't recall any injuries caused by it.
Thanks all - great discussion. I think there's a difference in the consequence of pre-binding, depending on where it happens. So, a pick'n'go off the back of a ruck will have far less momentum (and is implicitly less dangerous) than a pass back 5/6m, which gives the prebound 3 enough space to gain sufficient speed to flatten the opposition. The latter seemed to be the tactic Wasps employed time after time in the last ten mins of the match. It's that distance between starting point and hit that gave rise to the FW law in the first place, because it was deemed dangerous.
What would I do if it happened in a game I was refereeing? Once, I'd probably let it go. If it happened again quickly, I'd likely have a conversation at the next stoppage to manage it. If I saw it as dangerous at any point, then I would ping it anyway.