Trump is still a hand grenade to throw at the establishment.
They don’t believe the Democrats have their best interests, and a substantial number don’t believe Republicans have their best interests at heart - which is why it’s Trump or Bust.
This is fallacy. It may work to attract a certain type a voter but in practice Trump bends over backwards to appease the GOP. He lines his cabinet and campaign with GOP old guard and is set out to accomplish GOP policy goals. Not once in my interactions with any Trump supporters have they hinted at doing anything that wouldn’t be aligned with typical conservative ideology. Trump is the GOPs creation. Nothing more. Nothing less.