Vulture has a long interview with him:
It might have opened in first were it not for my insistence that I not participate in a worldwide press tour. The producers never spoke to me again after that. Ray Harryhausen wouldn’t talk to me for 25 years after that. They came to me and said they wanted to do this global press tour. I was really excited. They had all the countries we were going to, but the big kickoff party was going to be in Johannesburg. I said, “The one place I can’t go of all those places is Johannesburg because I’m on an anti-apartheid committee.” And they said, “What’s apartheid?” I said, “Well, you’ll have to look it up, but I can’t go.” And they said, “Well, that’s a problem because Johannesburg is underwriting the entire tour.”
He was also extremely passionate about cutting off Medusa's head with a sword and not his shield.