Yes of course people can 'poison minds' against one another, either deliberately or through a jaundiced opinion, or a mistaken belief. They can, though, have very good reason to want only supervised access to a child. In the case of paedophilic fathers, few people would think it reasonable to allow the man continuing control. In a misogynistic world, the people running courts, and manipulating systems, tend to favour males. That episode of Womens Hour is still available.
The mother knew something was wrong, when the girls began to be disturbed about visiting their father. But she had feared that the father had resumed heavy drinking, which had been the cause of the marriage breakup. (He had, too) It had not crossed her mind that there was the extra element.
The girls eventually explained there was something, not just the drinking, but that they couldn't possibly tell her. She suggested they tell someone else they could trust. That person persuaded them to tell the police. The mother still had not known up to that time.
Then, the police, social workers and courts fell straight into the trap the paedophile had laid of 'predicting' the girls would say it: But, by using the magic never-fail word 'alienation', the entire system turned against the protector and the victims, and played perfectly into his power. Even after conviction for abusing them and other children, the legal system allowed him 'ownership' of the children, and when he left prison, courts let him have sole custody. Fathers sexually abusing children is not especially rare. Protecting paedophile r pists with a never-fail free-pass magic word 'alienation' must be wrong.
(Protecting r pists and paedophiles with never-fail free-pass magic words 'I now identify as female' must also be wrong.)
The obsessive fervour of a now defunct (?) fathers organisation sometimes appeared creepy, red-flaggy and sinister. Their hatred of the mothers and determination to get control of children and get them away from mothers seemed unhealthy, unbalanced, and worrying. The same thing happened with Stonewall, (once a reasonable organisation for helping gay men who were discriminated against, especially with AIDs, especially in America, and, in those years, still with no legal same-sex marriage). Founding member Mathew Parris left, renouncing it, when it was overtaken with the creepiness and the hatred of women and obsession with control of children, and finally when the fetishists turned against ordinary gay men like him)