To be honest, he has kind of defected. Yes, he didn't mean to go to Russia initially, but he's chosen to remain there, knowing that the Russians can throw him in the jail whenever they want. By remaining there he's turned himself into Kremlin puppet, to all effects and purposes.
I think revealing the wrongdoings of the US government was honourable, but fleeing to Russia was a bigger dishonour. You don't have to agree, it's a matter of opinion, really.
I believe he was trying to go elsewhere, but got stuck in Sheremetevo airport because the U.S. disabled his passport before he could board a flight to Hong Kong (or elsewhere, I don't recall where)
In what way? Has he said or done anything that makes him seem like a Russian puppet to you? I don't see how being physically located somewhere means you support or agree with them.