That is one reason why it is so important he publicly repudiate his father Hutton's teaching and comments about Holocaust Denial and Antisemitism. It creates doubt as to why he made certain artistic decisions in the film where the New Testament is silent.
Honor thy father and thy mother: that thy days may be long upon the land which the LORD thy God giveth thee," Exodus 20:12
I think for Mel to publicly repudiate his father would not be to honor him. Devout as Mel is, I doubt he wants to violate the commandment even if he disagrees strongly with what his father says. That's just my scarcely educated $.02, though.