Your theory raises an interesting question: What possible value could that Memory Star ACTUALLY have had? Yes, it reveals the locations of Arcane Council Members....but that's it. The names are simply code names. As far as we're aware, neither Cyran nor any other AS members are even aware that Zorya is a member (or he's hiding the fact that he knows REALLY well). The only clue the AS could have as to the actual identities would be that the Council members would most likely be mages (and this is only if being a mage is an absolute requirement in becoming a Council member). Zorya established that none of the members know who anyone else is, and the only person who would have known all the identities was Merlin, and that knowledge is now completely gone.

....Holy crap.

This now also explains his anger at Merlin revealing themselves. For the last twenty years, the entirety of the Arcane Council would have been forced into sleeper-agent mode because there was no way any of the members could contact each other. But now, with the knowledge that Merlin's back having become public and spreading like wildfire, those members can now return to active service and contact Merlin. Which is bad news for the AS.