Zane has said that everyone was told this was going to be a movie documentary about bodybuilding. So no one was paid for their appearance- or they received minimal compensation. Zane said he could see very early on that it was going to be structured mostly around Arnold and then everyone found out that Arnold was being paid A LOT more than everyone else. Everyone was pissed but still wanted their chance at stardom so played nice. Zane said 'fuck it' and focused on some other business venture during the filming of PI. He said he definitely was not in his best shape.
I think Zane is a little bit of a bullshitter and as he's grown old he comes across a little bitter in some of his interviews. He's the only peer who I ever heard talk shit about Dickerson.
In all reality, Zane really doesn't come across as charismatic and he wasn't in shape so his footage was cut. He was set up to take over after Arnold and Franco. He was given opportunities, TV appearances, commercials, the art gallery exhibition etc... I doubt that he truly sensed any bias back then. I think its what he tells himself now.