Arbitration is usually an alternative to court. An insurance company will settle (yes, for somewhat less, but the plantiff's attorney costs are less, too) rather than go to court in a clear-cut case. And I think this would be true even if Terri did have bulimea.
Also, if her parents took care of her, who's going to take care of her AFTER they're gone OR can no longer take care of her?
The siblings? I don't think so.
They are young and have their lives still ahead of them. They won't want to give up their livelihoods w/childern to care for Terri 24/7.