Agree, I think the free bulletin board service type sites are ok.I'm wouldn't be surprised if some people who place ads on here would come under scrutiny based on the proposed rule.
No money for the transfer goes through the site. The site does not charge to place an ad. Although an account is needed, the accounts can be obtained for free. There's no way to imply the opposite. There's nothing they can provide to the contrary. The site makes no more or less money depending of if a sale occurs or doesn't occur or even if an ad is or isn't listed.
But I have to admit it would warm my heart and make me laugh hard if Gunbroker got shut down. That would be an epically wonderful day.