He definitely crossed the line saying..
“Kenyon and Carmelo carried two big burdens: all that money and no father to show them how to act like a man,”
“He was the best offensive player I ever coached. He was also a user of people, addicted to the spotlight and very unhappy when he had to share it.
Keep it focused on basketball. No need to go personal. Just shows what type of person Karl is. Not to mention that he's not that good of a coach.
However, I can't disagree with him on this
“He really lit my fuse with his low demand of himself on defense. He had no commitment to the hard, dirty work of stopping the other guy. My ideal — probably every coach’s ideal — is when your best player is also your leader. But since Carmelo only played hard on one side of the ball, he made it plain he couldn’t lead the Nuggets, even though he said he wanted to. Coaching him meant working around his defense and compensating for his attitude.”
When Lebron, Wade and Melo was drafted, my favorite player was Melo. I knew Lebron was a superstar, I got to watch him a lot in high school but Melo was a pure scorer with championship experience. So I agree, his defense stopped him from developing into the all-around superstar like wade and Bron , he wasn't James Harden bad, but he lacked effort and basic concepts.
He will never be a great defender, but Melo has matured a lot from his Denver days and his basketball IQ has drastically improved. He still have lapses, but you see him actually stepping up to the challenge of playing an all around game.
Anyway, this shouldn't be news ... Let Karl sell books on his own.