Safeword is vital for both parties. Doing a play party where two people doesn't even know each other well is like playing a Russian roulette.

I would be concerned and place a huge??? regarding with the Dommes action if he uses safeword. Fair enough, if the Dommes doesn't like the safeword, it's her responsibilities and obligations to protect her sub for safety reason specially where there are other people involved. As what everyone point out here...communication, communication and get to know what your limits are and be able to trust the person involved.

Lastly, use your common sense...