I promised you I would look up what the USOpen policy was on players being vaccinated. For some reason, it seems they are still undecided?
As to "stuff going on in the background," we all have to think that he has been in touch with the tournament. Surely they are speaking. As you say, we don't know if they've drawn a line in the sand as to deadline. But I will say this: if they have told him they'll let him go over the deadline of the draw, they'll want that in deep cover. Obviously, it is not only in Djokovic's interest that he play the USO, but in the interest of the tournament, too. But how would it look for the tournament if it came out that they offered him to blow past the deadline of the draw? Maybe not so good. Surely it would be favoritism to a top player, which is what led to so many bad feelings in Australia.
In larger world terms, it IS a tempest in a teacup, which is why the US Govt is not moving its policy in time for one guy to play tennis at the USO. However, in tennis terms, it's a big deal. Just like before the AO, and even IW, Djokovic has everyone pendant to his choices. Rather than back off gracefully, and stand by his personal decisions, he's once again got all of the tennis world wondering what will happen. You say he's earned the right to be selfish. I would say he's actually earned the right to special treatment, meaning waiting for him, but up to a point. For me, the point is when the draw is made. This is where I think special consideration ends, and I hope that the USO has drawn a line. If they haven't, I think they are collectively idiots and will deserve the criticism they get. And they will be criticized.