Every single shot within every single point has such small margin for error. Tennis is a mentally grueling sport. You have to be absolutely locked in at all times. Silence is almost necessary for peak performance so one guy being a douchebag can really make an impact. That's partly why the etiquette is as such in tennis. It's not the same as most other sports for those reasons amongst others.
With that said I do wonder if Naomi is refusing certain treatments that may help her because she fears the impact on her physical. It's a damned if you do damned if you dont scenario to her.
I would suggest a full reset of some sort for her. I continue to root for her and wont denigrate her for being bothered by a heckler. Its clear who has never played competitive tennis in this thread.