“ If any state tries to keep him off the ballot, or if the feds or any state tries to restrict his movement or communications, the USSC will slap them down.”
On what basis?
There are no Presidential elections in the Constitution, and there certainly isn’t anything about “announcing”, “running”, “delegates”, “conventions”, “debates” or anything else that people bring up about how suppressing Trump is going to involve a Federal Constitutional issue.
The GOP is a private organization, free to run their affairs the way its directors decide. There is no right to be nominated, no right to be on the ballot, no right to be invited to debate, etc.
The “two parties” have closed ranks. Their agreement about “no ideas that disturb us” is firm.
“On what basis?”
He does not need the GOP to gain ballot access.