Unless I'm misreading this (and I have the mother of all migraines at present so it's possible) weren't both the author of the post and Dave volunteers helping out rather than students? In which case shouldn't whoever was running the session just shut them down since the whole point is to help the people attending to learn rather than intellectual willy waving?

I used to be Dave when I was younger (still am if I don't keep a lid on it; I'm sure empathy is a wonderful thing but I've just had to learn to fake it over the years). So my preferred solution would have been to ask "does anyone else have any questions or are the rest of you secure enough in your own ability to not feel the need to advertise?". But then I guess there'd have been two jerks in the room and only one of them being helpful.