Considering everything shown in this chapter, it could also be that he unconsciously knew and recognized Guwon as his father's murderer and thus tried to kill him in return when he wasn't aware/awake. But I'd love to see an unhinged killer in baby Jinwoo so i like your theory more jejejjee
I feel like he killed his own dad tbh and thats he's warping his memories to what he wants to believe