There's a thing people are neglecting to mention, in regards to mysticism being involved here. A single traitor's name: Freyja. It's not beyond the realm of possibility that she has given info through channels (we know for example Akio has ties to the PsiCorps through what'shisname) to Earthgov, knowing it would be the single best way to spite Corwin given current circumstances.

The fact that she is (or was?) apparently over the kanmussu (and they're still being raised by her Gift, so signs point to 'is') of Valhalla is Doing Me a Heckin Concern, as the kids say.