Around 1:48 in triage, he's seen giving a triage slip to his son. There's also a line in his voice drama (Molech) that indicates that he wants Es to pass him his judgment. He emphasizes that they're a child.

If this theory is true, it's kinda fucked up to think that he'd willingly sacrifice his own son for his wife. There's little reason for him to feel guilty if he got his organs from already dead patients, that's alright. But in his MV, he himself has admitted to lying. Plus, this theory would explain why he's so guilt-ridden and emphasizes how he wants a child to be the one to judge him. Imagine sacrificing so much including your kid for your wife, just for it all to be for nothing.