Then keep note of the names if they don't want this shit to come up. VERY simple, and unlike you, I don't think they'd complain about having to keep 2000 names in the book, because I think they realize it involves only one name lol
In fact, I have a great idea! Why don't LSs that buy the stones make a "good times" post with the name of the seller every time they buy an autumnstone!? Oh wait, Jamal would come after you with his ridill if you do that. Is it dumb and tedious? Sure. You don't have to do this, of course. This is just to save your own face, after all.
Anyway, claiming ignorance obviously doesn't indemnify you from the accusations. Either
a) avoid it altogether by not buying at all or
b) have the name of who you bought it from so you can say "this is the guy, and we're sure he's not RMT" or
c) not give a fuck and just go about it.
It's your choice. But as the post count should indicate, no one is going to change their minds about the RMT situation no matter how hard you try to convince them. Arguments like Bajaratt's just increases the post count with no results.