We sometimes have that happen because we are kind of like a geographically unconstrained meetup group that lets anyone join.
If people RSVP though and show a pattern of abusive behavior with respect to guest speaker attendance, I will ask the attendees to consider flagging the RSVP, which would hurt reputation of the users involved and result in lower chances of them ever getting on again. In the case of peerplays this is obviously not the case because they are nearly always there. Something just came up for them and it might have been a good thing it did. The hangout as it stood was longer than the 2 hours we usually set aside...and that was with an extra 25-30 minutes we got from them NOT showing :P