I don't see Charlie doing personally dangerous things, and Charlie being a trimancer link would make the link with Vanna the Turnamancer pretty dangerous.
What's the positive reason for it over any other theory, though? Cuz I guess it could be the case, it just runs up against my usual complaint against a slew of ideas, which is it seems over-complicated compared to the evidence.
I suppose Charlie's hiding something, or why stay anonymous in the first place. I'm open to the Charlie is the Arkendish idea, and Charlie's another Parson gone native can't be ruled out. But really, it doesn't have to be some very profound secret to make sense. Charlie might just be some scrawny nerd of a caster who stumbled across an artifact and a capitol site, and came up with a strategy to keep from getting curb-stomped by royals, or inevitably worn down in the normal ebb and flow of open warfare.
I'm unsure what about the "Charlie is the Arkendish" would be a secret that would be so dangerous to get out. Or are you positing that there is another secret that he has been guarding by losing cash via inefficient managing of his capital? (Corollary to Charlie's Rule #15: Most things are not more important than money.) Or just that the history of betrayal (Corollary to Rule #3: Creating problems for our clients creates business.) is the secret It's been guarding? [As a side-note, if that is indeed out, will Charlie pop a single Warlord to act as admin to save cash?]
I'll concede that Archons are not true thinkamancers, but Charlie being a non-thinkamancer (or alloy of multiple non-thinkamancers) who knows the secrets of the G-Strings would explain the "IT" reference from Maggie -- they really don't like the idea.
I just find the link-up idea to be compelling, as the one time we see a Great Mind coming upon a trimancer link, he instantly thinks to unravel it.
Additionally, the additional danger to the Spell-that-shall-not-be-named (ie, the link with Vanna) would be a reason why Charlie isn't doing this all the time as a special service, and a marker of how panicked Charlie is with Parson.
Again, just putting it out there as a 'Hmm' not as an 'OMG, this has to be it!'