Can the state choose to ignore the results of a caucus?
Barring him from a primary is one thing - those are wholly controlled by the state - barring him from the general, without a conviction, is in direct violation of federal law.
Before this whole primary nonsense, you had to belong to the party AND be an active member to select a candidate who would run for the party in the “only” election. That’s why the DNC keeps breaking their own internal rules about who gets to run (like Bernie in the last primary) because these are private orgs and they can pick and choose their candidate and ignore the primaries altogether. It makes the party distrustful but hey, it works doesn’t it?
The general elections are the ones guarded by federal and constitutional protections.
No. the state merely administers the primary election for the parties if that is the method chosen for selecting the delegates to the National convention. Parties are not required to have primaries or even caucuses to select the delegates. The smaller parties like the Green Party, Peace and Freedom, etc. just have a national convention but don't have primaries or caucuses.