I am saying I don’t understand what you are asking. It sounds like you are asking us to imagine* some scenario where jerk John is somehow even jerkier, or his jerkishness is somehow highlighted in his treatment of Julian. It’s some reductio ad absurdum scenario that has no bearing.
John was a jerk. He was damaged and it manifested in how he treated Julian and Cynthia. He also wrote about, and in some ways demonstrated, a desire to be a better person. And wrote some brilliant fucking music. What more are you looking for?
*heh