Brian Epstein owned a furniture store. He was hardly "running the music business" when he met John Lennon. And being Jewish didn't do him a lot of good because he sold the rights to The Beatles music for pennies. If there was some Jewish conspiracy to run the entertainment industry he apparently wasn't part of it.
And John Lennon was a great songwriter but he was often bitter and liked to make songs about people with whom he had a grievance which often seemed to be based on jealousy, like Paul McCartney and Bob Dylan. Calling someone a rich fat Jew isn't really banter I don't think. Brian Epstein was hiding his sexuality and his dependence on drugs and alcohol. He died alone and unhappy while the Beatles were off meeting with the maharishi and they barely had anything to say about his death since they were currently in a frame of mind where it's all an illusion, brother.
This isn't really banter. Brian was shocked and hurt when he heard the song. John sang it to him in an elevator with some of their music business associates in attendance just to make sure he was aware of it. That's not banter. It's deliberate mental cruelty.
And your own argument is incredible. First you want to use the very tired "you can't say anything anymore" argument, and "people don't even know you're just joking ffs" and then you dive right in "but it's true that the jews own the music business!!!!"
You try very hard to say things in a clever way so that no one can pin you down on your views but you can't help yourself.