Wasn't it said Whedon had favorites? I can't imagine Head would fit into Whedon's M.O. He's an older male with standing than young female newcomers who Whedon can easily take more advantage of and exert power over, so I can't imagine how Head would be a witness to that. Judging by his abuse, it wasn't in the open, Scott Rudin abusive, it was more petty person to person where Whedon could just sit you down in a room and do it that way more passively even.
It always comes down to power. It's intoxicating, especially in this industry. Especially when you are in charge of attractive young women and they are in your story. My friend said it best, power reveals. It's more of an ownership thing. His female casting and their intentions is coming off as more fetishistic in hindsight. Granted, great actors in their own right with terrific acting where I can still enjoy their characters for what they are, even the stories, but from now on, I'll have to take a beat and wonder what other subtext there might have been from its creator.