Funny you say that this is what a friend (who also DJ's from time to time at the venue) has just emailed me:
Personally, I would refuse to sign it and so would any other DJ or entertainer, I'd imagine. It's the very thin end of the wedge, so far as I can see and in effect nullifies any attemmpts to entertain, if our actions are going to driven by "I hope someone doesn't fall over, hurt themselves etc etc" whilst being entertained.
So, we don't play rock and roll, the twist, or any other type of music in case someone hurts themslves? Ridiculous.
People are there of their own volition and know what the risks are. We don't force anyone to dance, do we?