If the courts were designed to be fair, I could see this working. But fairness is only an occasional byproduct of the ‘justice’ system. What its really optimized for is repeatability. And the US governemnt has been found again and again, to not need to comply with its own contracts. Its the puny individual citizens who must meet their end of the bargain.
As I mentioned before, the magic words “national security” dissolve all notions of fairness or logic.
Plus, Im doubtful any US court would accept a legal argument from Snowden in absentia. If he were certain of himself prevailing, he could certainly show up and take that chance, but… yeah.