Why would China or Russia deport him or detain him any longer than necessary to strip him and squeeze him a bit? It's not like he's getting any new info, and this way he remains a source of political destabilization for the US.
Oh, plenty of possible reasons. For example in exchange for some captured spies or hardware. Or some other concessions.
He also may have access to material nobody published yet. Again, it's not about what happened, but what he would have had to fear if he didn't have contact with the Chinese or Russian government before fleeing there.
