and would they still interfere if you ask them not to take actions in that forum?

Well honestly this would be the easiest solution.. Unless you assign a Mod to that forum, no Mod's can moderate there but this does not apply to S.Mods or Admins. To prevent their moderation by hacking requires WAY a lot of modifications.
As for S.Mods you can disable their access to this board via access masks but I guess you wouldnt like this solution..