It’s probably less about active measures to slow it down. The postal service is a cluster as it.
What any normal country would do is say they’ve just gone through disastrous primaries. A lot of investment should go into the postal service to ensure the general election is smooth. And then you’d do other things like set early mail in deadlines, and have a two-day in-person election etc (to ease pressure for social distancing and sanitizing). Stuff like that would have happened already if you were interested in protecting the integrity of your election.
I think Trump assumes anything that limits access probably hurts poor and younger voters and therefore hurts Democrats. Also he’s seeing Democrats lean into social distancing, so not investing in postal services is to his advantage. He’s encouraging his people to proceed as normal, so he’d expect polls to be filled with republicans.
