I actually think this sounds reasonable, from the other guy's perspective If this guy sounded like a friendly, open minded guy trying to learn what works, and not trying to hurt anyone, then letting him do his attacks and seeing what happens is fine. I would never do the move in a gym, but if he warned beforehand, and used it as a choke, but did not put enough pressure to risk injury or pull back or anything violent, it sounds okay to me. That's why I always look into places before I visit them; I want to know what I'm getting myself into.
But if he gets desperate and starts being too much of a dick about, see everyone's above posts about how to respond.