We have several points where the Sunreavers or those over them use resources from the Kirin Tor meant for neutral use, I exaggerate nothing, THIS was why the Reavers were in hot water.
At Garrosh’s trial a Sunreaver WAS convicted of opening the portal, after an investigation this is one instance. Thalen is another with the Manabomb, Thalen then allows the Horde fleet entrance by abandoning his post (this is a third treachery, albeit by the same Sunreaver), Fanlyr steals the bell using a portal opened by the Silvermoon mages and an unnamed Sunreaver (this is 4), etc. that’s 4 different times the Sunreavers either used their membership in Dalaran to backstab the Kirin Tor or gave resources to someone else to do it instead.
These are all 4 instances of abuse of Kirin Tor rank or resources available to the Sunreavers within about a month period. between the 4 of them accomplishing two events of mass devastation (especially if we take into account the fact that the Divine bell incident in testing originally had the bell used in Dalaran).
There is likely more hushed behind the scenes, seeing as neither of these two things happen over night.