I'm not defending what he did at all. If you walk out on your team like he did, you don't deserve to be on it anymore. Even if you're suffering from an injury or mentally ill (or both), it still makes you responsible for your actions.
That said, this man is suffering from CTE and is mentally ill. Notice all this bizarre behavior with him started after he got hit by Burfict in the playoffs back in 2014. CTE is a real problem for a lot of players, and even though the NFL now has a concussion protocol, it doesn't account for the non-concussion hits to the head players take on a weekly basis during the season.
It's really sad that things ended this way for AB. I hope, if it's the last thing they do, that the Bucs get him some professional help and I hope he's willing to receive it. Don't bash AB for what he did, instead, say a prayer for him.