Not sure the plaintiffs would have any standing to bring such a lawsuit.
The Republican Party and its various state affiliates are basically a private organization. The main party allows state affiliates to set their own rules for delegates.
In order for a plaintiff to sue, he/she would have to sue the party affiliate in each state regarding their rules for delegates, and the plaintiff(s) would have to have legal standing in each state.
I don’t see any Federal judge wanting to stick his finger in that mess.
Never underestimate corrupted judges.
This type of lawsuit gets complicated. Essentially the plaintiff is arguing for his “individual rights” vs an organization’s rights. Organizations do not have first amendment rights that are easily definable.
I would guess that the party will be able to do an end run around this while still honoring his right to vote.