100%. Mueller had no choice but to turn over his report to Barr; not to do so would have been illegal.
If anyone was disloyal it was Barr himself. The Attorney General of the United States owes his loyalty to the US Constitution, and therefore, to the People of the United States, not the Criminal-in-Chief in the White House. The AG is the People's lawyer, not the President's lawyer!
I, (name) do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I take this obligation freely, without any mental reservation or purpose of evasion; and that I will well and faithfully discharge the duties of the office on which I am about to enter. So help me God.”
Barr then proceeded to break that oath almost the moment to took office!