Public enemy number one for Democrats is whatever Republican they think will beat them. It's the candidate they fear the most. They hate Ted Cruz, but he may not be the one they fear the most.
I think you’ve gone a bit astray with your analogy. I also think Trump supporters have thin skins and short memories as a general rule. Cruz having fun with Trump because Carter prefers Trump to Cruz is almost as bad as Trump calling Carson a violent criminal or pathologically tempered, no?