If the biological was about anything his son would not have kicked in the door and punched his stepdad in the face because he was to hardheaded to listen to instructions.
I doubt it.
People don't know how to read between the lines. How many people stay strapped in their home?
They had an argument. A fight broke out. He had a gun on his person which shows he approached the conflict with malicious intent. He got lumped up and shot him several times.
The argument stemmed from him kicking the door in after being locked out of the house. Locking someone out of the home is an act of aggression that would provoke conflict. You can say that he was rebellious for leaving the home but then looking at the hate in the man's heart, I don't blame him for wanting space.
Regardless though, I would take his son. And then talk about how things played out. It is a matter of principle.
People want to get on that jungle shyt when it comes to another man's seed, it can go that place in the extreme.