Unfortunately, I think you have to examine the person as part of this process. When the person starts a stupid fight that gets him and the starting tailback ejected from a game, that's a problem. When the person gets your team in 1st and 35 because he can't control himself, that's a problem. When the person is getting himself on TMZ for bad reasons during the middle of the season, that's a distraction. When the person is throwing his teammates under the bus through his agent because he's mad at the front office, that's a locker room issue.
I don't think he is a selfish person, but he's a very impulsive and petulant person at times. When you're looking at allocating a significant chunk of your team's resources to this person for an extended period of time... it HAS to be personal on some level. Trust matters.
And again, I feel like this is the sort of issue where if the Dolphins move on from Landry, fans will bash him. If the team keeps him, fans will love him. I feel like he deserves both the love and the scorn. It's all going to be personal from here on out.