Leaving aside his other comments about Trump, I don’t think Barr is entirely wrong in saying that Trump and/or many of his supporters want to burn the GOP down. Especially if he doesn’t win the nomination.
Even if he does.
I really believe that the GOP RINOs, starting at the very top (Mitch McConnell, Lindsey Graham, and quite a few more) are actually at the very root of the problem, and need to be replaced ASAP.
The GOP is in severe need of a major overhaul!
I've only seen RINOs trying to burn the GOP down when they don't get the nomination. I haven't seen Trump do that.