If you get 100 applications and can only take 5 in an OAF event, there are still 95 other candidates of which some might find $150 to be a nominal cost to avoid this sort of scrum. Its admirable that folks are protecting startups from obvious scams but its dangerous to get overprotective when the end result is that you remove a reasonable option from the table. For $150 you get a sit-down with smart people and will at the very least get practice pitching under pressure and good feedback.
And at $150, we're talking picking up the tab for a nice steak dinner, which is something you've advised numerous times.
If these dudes have invested in companies they met through this type of forum, all the better. And there's a certain amount of due diligence an entrepreneur should be expected to do -- no need for the rest of us to protect people from their own stupidity.