Because anyone in their right mind would also try to act like a father if they found out they had a kid...?
Girl I think you missed the fact that Duke Escra didn't know that Camilla existed until recently
he has a kid before he knew camilla existed why didn't he try to be a father to Dive? He's trying to be a father to Camilla but not to Dive
and he knew Dive existed but didn't act like a father to him but to Camilla he's being a father after he knew she existed
Am I the only one being creep out by Camilla's bio father's action and attitude? Like why try to act like a father now (I know he lost his memories but still) and calling out the Sorphels regarding their treatment to 'og' camilla being harassed and bullied when he himself turned a blind eye to Dive's abuse. If Camilla didn't interfere, he would just continue to neglect Dive.
So that bio father can gtfo and go back to wherever he came from. Let camilla be happy with the family she's supposed to have after coming back to her original world