If you want the official line on the area, also check out 6th World Almanach. It is very limited (got to be expected, when comparing it to a bunch of previous books dealing with 'only' 1 continent or even a single country), but it does have some info on Argentina and Amazonia, as well as Aztlan.
Back on topic - the AI theory sounds intriguing. I have never fully read through my copy of Emergence, so I cant judge it, though.
If itīs an Azt insider, it might be Oliver McClure (sp?), the nice guy, that Dunkelzahn bequested with a seat on the Aztech board. He was pretty outmatched in his struggle to make Aztech a better corp as of late, IIRC (Corpguide I think), and he would have verry, verry good reasons to hide his identity, if he was the sorce.

Or maybe it could be ... Juan Azcapotzalco, the zombi CEO from beyond the grave. I never quiet bought that 'bombed at the peace summet' story, after he had vanished for so long.

@ Frostriese
It was Leonardo Da Vinci, not Michelangelo. Was he really killed by SK/Lofwyr? Never read the Novel, from what I got out of Blood in the Boardroom, he just vanished and SK bulldozered his shak. Could still be the same Salai, but I donīt see an Aztech conection, either. Seems unlikely, he joined the Azt-Guerreros after his master left, but who knows.