Loyalty to me, but not to thee

Good. Let him. That way in 2024 Biden or Kamala wins in a landslide due to vote splitting

That's precisely why they shill for him.

Well, that and putin has kompromat on a bunch of them.
https://www.thedailybeast.com/cheats/2016/12/10/report-russian-hackers-had-rnc-data-but-didn-t-release-it
https://www.reuters.com/article/us-usa-russia-cyber-rnc-idUSKBN14U2DD

I reckon this is what you're saying, and I think you're spot-on with it.

Because he has a good 20 % of the voting base locked up tight, and another 20% willing to follow him (but pretending they don't like what he's doing) When you own half the voters, you own the party.

Also, they're all a bunch of authoritarians so falling in line is what they want to do.