the states determining their own political processes AS THE US CONSTITUTION GUARANTEES THEY CAN by not saying they can’t.
You brought the constitution into inter party disputes, not me. The parties CAN do as they please in regards to primaries, just as I can point out the system as exercised in Colorado is corrupt. The state governments can do as they please, within equal protection limits, but the state parties are not part of that structure.
While the Feds are limited in what they can prescribe, the GOPee can make rules for participation as they please...they can say, "You have to run your GOPee processes in a certain way, or we don't have to recognize the result." Shame on them for not doing so.
That's an interesting mindset you have...you do recognize there's a constitutional difference between state governments and state parties, don't you?