it's a group of musicians who enjoy playing tunes they all know or join in if they want or sit back if they want

Um, I think Charley's entire point was that it wasn't like that.

"...played perhaps their fastest, flashiest and 'show-offy' tunes to the total exclusion of everyone else ... did not enjoy my offering (wonder why?), making sly comments, making faces and then immediatly excluding me with two sets of tunes in their aforementioned arrogant style. Said tunes went on forever..."

Sounds like they were having a lot of fun - partly at Charley's expense - but it doesn't sound like much of a session for anyone else.