That bully is a reason why on railsgirls events you have tables for differen skill levels. You could easily send that guy to another table with more advanced people without throwing him out.
His point was that in practice, students who actually already know basic programming test out of the intro class, but there always seems to be a contingent that _thinks_ that they are experts, and who ruin the class dynamics by acting superior, asking show-offy questions, etc. It would be better for everyone if they could self-select into a single section.
(In fact, in my evil little mind, I might be tempted to send a Dave to a table just a bit above him, to show him that he's only hot shit in his own mind.)