Why do you suppose people request asylum from third-party countries? Could you describe a circumstance in which it is a legitimate request should be granted?

Regardless of how you feel about whether his criminal charges are political there is nothing extralegal about requesting other countries to turn over the person you've charged with a crime.

It cannot be extra, meaning outside, the legal system, when all you have done is made a request within the established legal system and diplomatic customs.

We have no idea what kind of pressures the US has brought to bear against those considering his requests.

He has the right to seek it. Closed door pressure against those who can grant it is very certainly extralegal interference.

If they have any legitimate legal reason to interfere with his asylum requests to third parties, why not just charge him with a crime that those third parties would see as valid, or exclude torture from his potential punishments?

This is not about extradition, it's about asylum. Presumably you only grant asylum if you believe an extradition request is bullshit to begin with.

The US only has one non-scumbag move here, and that's to charge him with a crime or crimes, and make a credible commitment that his potential treatment before, during, and after the trial doesn't violate his basic human rights.

Going behind closed doors doesn't suddenly make the charges more plausible (espionage? really? he gave the info only to journos, spoke to no govts) or magically clean up the US's history of human rights abuses and torture against enemies of the military, be it Manning or al-Awlaki.

Bad or good, guilty or innocent - it is always wrong to turn someone over to be tortured.

Are you suggesting that Snowden is aware of these backchannel threats then?

The US isn't in the habit of ensuring that the rule of law will be fulfilled since that is still the default posture of the government.