Absolutely! He's guilty of the crime, but the mother's guilty of not protecting her daughter from the same man Mommy divorced a decade earlier for raping (twice) her own (then) 14 year-old sister. I bet the little girl wasn't fully informed of what her father did, and even if she was, isn't it Mom's responsibility not to leave her daughter alone with a sex offender??
It's letting the fox guard the chicken coup. Only in this case we're talking innocent, precious, children.
Notice that the mother told the elderly neighbor that the father wanted to see the children but "her boyfriend said no".
An unrelated individual - not even a stepfather - has better protective instincts regarding the children than their own mother.
Execute the father - supervise the mother who either has the IQ of a turnip or is a total doormat (maybe both).