if Trump admin proceeded on the pardon post-haste, and called on him to be released, and condemned UK for holding him as a Soviet Union style political prisoner, then if they were to do that to him it would play right into that accusation giving it full substance
the thing is that he's in their hands so this might be the best that can be done for him at this point - to start putting pressure on UK to release him because he's no longer sought by US for any charges and should be a free man
nothing to stop them from doing that now
if Trump admin proceeded on the pardon post-haste, and called on him to be released, and condemned UK for holding him as a Soviet Union style political prisoner, then if they were to do that to him it would play right into that accusation giving it full substance
the thing is that he's in their hands so this might be the best that can be done for him at this point - to start putting pressure on UK to release him because he's no longer sought by US for any charges and should be a free man