He doesn't
always hide behind characters. And perhaps you didn't read the whole discussion, but I already commented on the real world FZ. Banging groupies was his vice, to his wife's dismay. He
says so on camera, adding that Gail grumbles, but what's she gonna do? She's his wife.
When Marc Maron asks Moon Zappa on his podcast about weird things growing up in the Zappa household, she tells him they had groupies living with them. He also managed the GTOs which was a group made up of groupies.
The very likely reason his vices don't come up much is because if you are a documentary maker, you need access to material - the Zappa vault. You're not gonna get it unless you cooperate with Gail Zappa/the estate and agree to terms that will basically protect the legacy of FZ.
Gail is fiercely protective of FZ's legacy and everything else, even suing the Zappanale festival for using the iconic Zappa stache in their marketing.
He was by and large a good dude and a genius, but by no means a saint. You believe he was above
misogyny?