If we're going off what was written in the OP then he has not engaged in BBFS so that is not what might put him on any DNS list. I would agree, that if he is looking to go bare and not interested in covered service that a lot of providers are going to say they don't provide that service and send him on his way. But I don't think just for asking and being honest about his goal is going to put him on a DNS list as that is generally understood (i.e., this bridge is now burned).

 
This is the Newbie board, and even if it's not a newbie posting maybe keep the tone a bit more low key?

He's not a risk if he wears a condom, I mean no more risk than someone else wearing a condom. Sex workers ask for condoms because they want as little risk as possible so for their own safety,   they assume every client has had sex without a condom. Again, I have asked several times (not always), using a respectful tone and most times I get a no and I carry on (and most of the women I see are quite intelligent) and we have a great time. No one has ever asked me to leave for asking. Terminally naive? I've been at this for 25 years.  Use your head. If you don't ask for for bbfs, doesn't mean you haven't done it. I mean who hasn't? We all have on the non-professional side of life, if not within the profession. Geez.