I don’t think it will matter much. I am a veteran and I do not care what is said about McCain. The man is a slimy piece of work.
More attacks by RINOs just increases the esteem of those who have had enough of the RINOs.
The others were never going to vote for him anyway.
My personal belief, based on nothing, is that Trump and Cruz are a team and that Trump really doesn't want to be POTUS, but he wants to change the landscape. At some point, after all the RINOs are whimpering in a smoldering heap, he will withdraw and tell is supporters to move to Cruz.
If the objective is to prevent the GOP establishment from shoving another RINO down our throats, it's about the only kind of plan that would actually work.