My $0.02...
1.) I think suing would be pretty
ineffectual because you've got dozens and dozens of potential
plaintiffs. And something tells me that Mr. Beall isn't
independently wealthy by any means. Maybe a better solution
would be to find a high school team that's never done
well at Chip's tournaments and tip them off to the
existence of the question archive. A few nasty upset wins
might be all that's necessary to stop Chip from
plagiarizing the archive.
2.) Why not make the archive
free, but password protected? Whoever owns it...I don't
know if this would be feasible, but you could say on
the front page, "Because of recent issues of
plagiarizing for the profit of other entities, we have decided
to password-protect the Stanford archive. You can
get the password by registering your name and, if
applicable, team with whoever"...and then when Mr. Beall
writes, politely inform him that he's the reason the
archive isn't being made completely public anymore. I
don't know if that'd work at all, but...