When it's a teammate and one that is from Chicago, it is clearly easier for him to look past.
He is arguably the GOAT, but he's shown time and time against his passive aggressiveness and pettiness. Many call KD soft and a cupcake, but LeBron has shown many times that the slightest amount of criticism bothers him.
If this really stems from the "as a father" comment, it's weak from LeBron.

. It's the easiest thing for him to hang onto in this "beef" as he knows people will automatically defend him about someone commenting on him as a father when it wasn't even a terrible comment.