He may accept the Lord and forgive the father... it is still up to the father to forgive too, the Lord judges him separately.
Forgiving someone’s sin against you without them asking for it and truly tepenting is not the behavior of a Christian.
I understand that we are supposed to abide by the rule of law, but if you came in on an adult molesting your child, you would do - what?
As to forgiveness. Jesus teaches that we are to be willing to forgive, even if the one who wrongs us asks us “70 times 70” times for forgiveness, just as God or Father has forgiven us.
But, did you notice that Jesus said that we must be willing to forgive the one who “who asks” for forgiveness? That means the one who violated this man’s child must ASK this man for forgiveness for what he did to his son, and he also needs to apologize to the whole family and to God. If the family has difficulty extending that forgiveness, I totally understand and would not judge them for it at all.
God Himself does not blanket forgive everyone without first there being from the individual a confession of their sin, repentance, and asking for forgiveness.
If this molester never asks for forgiveness of the father or the family or God - his sin remains. Forgiveness cannot even be extended by the father of this child until the molester asks. The only thing this father can do is release his anger and hurt to God. Otherwise, “forgiveness”, “restoration”, is not possible without confession. Only a release of the hurt and mental pain.