It's one thing to theorize that AB has CTE and it's the cause of his recent publicized actions, but it's something totally different to say that he's only acting this way because of CTE and it is the cause. People spiral out of control all the time. Did Brittany Spears have CTE? She started acting erratic seemingly out of nowhere. Google Delonte West and see what he's up to recently. It's a sad situation.
As RU4Real mentioned (albeit in a humorous manner), the only way to confirm CTE is by dissecting the brain, which obviously you cannot do until he is dead. So, if you're inclined to believe AB's actions are the result of CTE that's fine, but it's only at most an association, and more likely mere speculation, without the benefit of a full differential diagnosis.