First, let me say: what?? I'd lol, except it's anything but funny when they do it.
Ok. Given that, I need to ask what the distance of their attack is while they're dancing. It seems like they're suddenly surrounded by a barrier of an additional tile or three of PBAoE damage, to which I say, again: what?? They're beavers, not whirling dervishes. Being basically unhittable and striking on all sides is bad enough.
Just my punch-myself-in-the-face-frustrated opinion.