My take is that he was trying to play both ends and it backfired.
He wouldn't have given Lindsay Graham a pass on saying weird things, and he hasn't in the past.
Had Rand Paul or Ted Cruz (who Rush has called a "true" conservative) said some of those goofy things, He would say something like "Folks, I just don't understand it, it makes no sense".
Yet, Trump goes off and Rush says "Well, that's just Trump being Trump".
I didn't send Trump people into a tizzy by saying that, they thought that meant Rush was okay with it.
Also, it was supposed to be signal to the non-Trump people that he was on to him.
He was trying to keep an audience by staying lukewarm, which isn't how he built his career.
He used to often say things like, "Folks, we're the ones who are supposed to be better than this".