This is the same kind of disrespect whether it comes from the bar staff or a fellow musician ,it seems this fella has a chip on his shoulders and needs to be taken down a peg or two , maybe he was just trying to gain popularity with the two new arrivals for when it was his turn at the mike,
I would not WALK out of this session because as you say Anti Arrogance it is unique and who knows what kind of talent may come out of it.
Tell us more , is this dick head the only reason you are dissatisfied ?