Step-parent adoption - boy’s perspective?

Has anyone had a little boy be adopted by your husband? If so, later on in life did you boy care about why the bio dad left? Did he not care did he want to talk to him? My little boy was adopted by my husband in 2020 when he was 3 1/2. The dad physically abused him in July 2018 and walked away. He signed away his rights and hasn’t tried to contact or talk to him since. As a boy, would you care about him and want to talk about him? We’ve been open to our boy about him being adopted so it’s not a shock to him later. We’ve slowly explained it for him age appropriately. My husband thinks he will want to know one day when it connects more and he’s older. But he said as a male, as soon as he heard the story and about him walking away voluntarily he would just think fuck that dude and not want anything to do. Anyone have any experience or input when the time comes?