He was too young to understand the material during much of the show's run (at least I hope so). Now he is an adult and he does not care to do certain material, I am sure his contracts were signed when he was still a minor (stage parents). He's just a 19 year-old kid. I'm sure he does care about and respect the people he literally grew up with. He can like the people but dislike the scripts. He's an easy write-out and will save the show a lot of money if he is let out of his deal. Lorre is probably thrilled to save $300,000 an episode.