Another thought on Margo's situation- now that she's known to be alive, what if Arkady (was that his name) went to the western authorities and basically told the story of how Margo was strong-armed into working for the Soviets when he was strangled half to death right in front of her. Might not win them over, but it might soften them up a little to their situation and open the door to some double-agent dealngs that could land her back in the States eventually, albeit in witness protection or something like that, probably. Everyone in the U.S. government probably groks that her 'statement' was written wholly by Soviet propagandists.
I doubt that would fly with the authorities - she did commit treason and defected, reasons don't matter in such cases. The US has been deeply embarrassed politically to have such a high profile person defect and if they ever get their hands on her she will stand a very public trial so the US could get some face back in public opinion. This is not the post WW2 era anymore where the US looked away when they chased ex-Nazi rocket scientists in order to get a strategic advantage, they will crucify her if she ever returns.
Or at least that's what would happen in a realistic scenario ( think Snowden) but this is a TV show so who knows.