Another option to consider is the ability for the GMs to send private bulletins to other GMs of the problem player(s) who are making the choice to abuse their given powers. This hopefully would preclude any public flaming of the cancerous player(s). Most GMs, in my opinion, are mature players who understand their role as leaders and respect the Guild's integrity as such.
Unfortunately, the few cancerous gamers who make an active and willful decision to undermine the integrity of the/any game will always be present. If this private bulletin system is implemented then they are forced to create alliances with other cancers and are segregated to themselves, by themselves, without further disruption.

Thank you for listening.