You said — “That means that the ATF know who the gun owner is. But apparently they are sitting on this information.”
Well, now that’s an interesting development — if it’s true. It’s hard to imagine a poster being that gun dealer, though. I don’t know; maybe so...
But, if they have the information on his identity, I can see why they would want to hold off saying who he was. They would want to run down leads and connections, first, talk to people, investigate other things about him, before it all became public.
Regards,
Star Traveler
Because the buyer may not have been the shooter.