"I know of a man who was involved in a divorce where his wife made a claim he molested his daughters."
That's horrible. It's horrible when it happens for real, and equally horrible to falsely accuse someone of it. Your friend's accusations are purely he-said/she-said. Did the daughters corroborate the story?
They were so young they said what their mother told them to.
Nobody has asked them seriously now that they are older.
Their mother doesn't want them "traumatized" you know.
She has badmouthed him for so many years, the girls wouldn't dare say anything else.