Quick to talk about how the Francis Schaeffer name made it possible for him to make money, I suspect the same is going on here. If he can’t get cash supporting dad, then he’ll get cash bad-mouthing him.
I attended a Scheaffer seminar in about 1976, after reading all his books. I listened to both father and son; my impression of them then was the father was humble and honest, while the son seemed to me an insufferable, self centered prig who would one day embarass his family.