If a country agrees to grant him asylum are they under any obligation to stick to that agreement?
i.e. Can he just apply to as many places as possible, and trust whichever of the offers he likes the most, or does he have to worry that maybe a country would offer the asylum while having a secret agreement already in place with the US to extradite him as soon as he is in their power?
That would be Non-refoulement, and a major violation of the UN agreement. I am not sure of any physical consequences to the country that does this, beyond a damaged reputation.
i.e. Can he just apply to as many places as possible, and trust whichever of the offers he likes the most, or does he have to worry that maybe a country would offer the asylum while having a secret agreement already in place with the US to extradite him as soon as he is in their power?