I mean, I'm not saying that's not possible. I'm saying it was the opposite case of your first claim. They need to move as quickly as possible to implement the guidelines before Sept 3rd. If they don't make it in time, some states will have already sent ballots. It's more than just USPS involved here, they're only one part of the "guidelines" Trump wants.

The postal service, like the courts, is slow to adapt. So are the states.

All of that being said, those lucky enough to live in a state like Washington or Oregon can already cut out the postal service entirely by printing ballots at home and dropping them off at the ballot box. The postal service has no power to block the ballots that way other than the inconvenience of printing at home or a library. I have exclusively used ballot boxes the entire time I've lived in WA, and if fuckery does happen (which I wouldn't be shocked by), I'll print my ballot and drop it off.