It's only too bad that Bart has not appointed you a moderator. Wouldn't it be nice to decide who is worthy of posting here, and who is not?
I suppose that the rule could be that you are not allowed to be a member on both sites. Choose one or the other. "Your are either wid us, or your again us."
I can't imagine either site doing this. Its an anathema to the spirit of the sites. If Bart had a mod it might be seen as kind of a conflict by the membership if that person was also a mod on BG, and it probably wouldn't happen. I prefer to see the site's "cultures" evolve naturally. I think that is an ethic that both sites share.
Both sites are amazingly free and open compared to some of the heavy handed, over moderated, micromanaged hellholes out there on the net. If someone was banned on either site, perhaps that is a subtle clue that they might belong on the other site. If they get banned on both there is probably no hope for them anywhere and the probably shouldn't have a computer.