Dygear, the article in Autosport (about 3 weeks back) stated some, unnamed, McLaren personnel are privately concerned about Hamilton. Yes, McLaren as a whole might not care what he does, but some people within McLaren do.
Also he is representing McLaren, so they do have an interest in what he does. But I don't think his head is in the game any more, he's more focused on what his management tell him to do.
Also, consider the fact that all through his career, McLaren have supported him and he's been in consistently good equipment. Does he know what it is like to be in a bad car?