"Were you lucky enough to have everyone stop and make way for you? were you accepted into the session with open arms?"

No, and I would not have expected it, and still would not. Anyone going to a session is advised to do so in the knowledge that they might not fit in, for any number of reasons.

But if a band is booked either to lead a session, or to play a sort of gig at an event that has been named (wrongly, perhaps) a session, then I think the organisers would expect them to show willing, and to engage with whoever turns up as best they can - and that would be the most professional approach anyway.

If no-one has been booked to lead a session then it mostly goes with the majority, but as I understand it, this was not the case here.

Tom