As far as I know, Jagex has told p-mods they cannot HOST dice/trust games. They are allowed to partake in such, however.
And as previously stated, there are p-mods that work "for" or "With" dice clans in order to mute rival clan-members. This doesn't happen much, however but it does happen. Normally the p-mods just mute players trying to act as impostors and who are trying to scam.