Didn't he go to Hong Kong first, then leak the information? You can argue that he would have been picked up in the US had he stayed, and you're probably right, but if you depart in advance you can't properly be said to be fleeing, plus it's pretty understanable that a government would look askance at a person who a) leaked to a foreign media outlet, and only to a foreign media outlet and b) did so from the territory of a strategic rival (as opposed to some neutral place like Iceland, or Sweden, which have generous criteria for political asylum.