Okay, so. This part looks like Edgeworth needling Phoenix, trying to make him look like the bad guy before Cody is summoned, but I don’t think that’s the real reason for him saying this. Cody is a couple of years younger than Miles was at the time of DL-6. It’s not unreasonable to say that Miles… is genuinely worried about Cody. He’s speaking from experience, here.

Granted, it’s not confirmed that Miles was summoned as a witness after Gregory’s death, but it’s really not unreasonable to assume that he was. He remembers being pressured by Hammond, and he’s genuinely worried about Cody’s wellbeing, especially since he’s only ever seen Phoenix on his full offence. He’s worried that Phoenix might accuse Cody of murder, when he, himself, is still living with fear and guilt over his own father’s death..