How were they negligent? Being unwell and collapsing on a tour could happen to any artist regardless of how fit they appear to be at the beginning. He signed up to do too many gigs thats for sure but it was a business arrangement and as the artist MJ and his management should have cut a better deal or renegotiated when they found he was struggling. Perhaps they should have claimed against the insurance?
Again it probably all comes down to money and both parties wanted to make as much cash as possible. MJ was just as much to blame, he knew he wasn't up to it. He would have done one or two gigs then pulled out claiming ill health. He miscalculated and it cost him his life.
Tour companies have a duty of care to their artists. If they can see that they are not physically up to it then they shouldn't "shout at them so loud the walls are shaking" and threaten them with financial ruin.
They knew from very early on that he wasn't up to it. Remember the press conference in March 2009? There was an email from an AEG exec on that day saying "MJ is drunk and despondant in his hotel room and is full of self-loathing and doubt now that it's show time".
There are other emails where AEG execs talk about how they are going to mislead MJ in business meetings about how much money he stood to earn from the concerts.
They were negligent by agreeing to hire a personal doctor for MJ without checking out that he was in a lot of debt and therefore may not have ethics at the top of his agenda. They also didn't provide the doctor with the necessary equipment he needed.
They had no care whatsover for MJ's failing health and he subsequently died at the hands of the doctor they agreed to pay the salary for. I'm not saying they are directly to blame for his death, but they were negligent along the way and certainly could've avoided the end result.