I had this very thing as well at a "session" connected to a festival here in Scotland this weekend. The afternoon session was fine but the evening session comprised the aggressive and arrogant behaviour from a couple of "important" individuals like you described. Nothing was said to me, but it was to others, with an "inner circle" clearly being formed and it was reason enough to pack away the instruments and go. Fortunately, though, I still find this sort of behaviour to be in the minority with the vast majority of sessions being welcoming.

Zen