As I've already said, you wouldn't diagnose CTE (or any other neurological condition) on one behavioral event. Behavior is just one of the factors you would consider when making a diagnosis and, even then, the behavior would need to occur consistently and somewhat regularly (as is the case with Mark).
Listen dude, I'm not really arguing about whether or not CTE is "a possibility" or whether it's "highly likely." On this point, I think we can agree to disagree. It's semantics. The people who I'm arguing with on here are the CTE deniers, the ones who categorically deny that CTE is even a possibility.
I'm not trying to be dismissive of CTE or any mental problems. It sounds like you know what you're talking about, and at the very least you know a hell of a lot more than me about this stuff.
What I'd say is - just as you're saying people shouldn't be dismissive of CTE/Mental issues - you probably shouldn't dismiss the possibility of those NOT being an issue.
His brain might be wired just fine - and he might just be having some maturity issues, going through some tough times, and is making bad decisions. Which given all that's happened in his life is totally understandable, but also not an excuse for his actions.
I've said this before - but all these posts are "what's wrong with Mark, I hope Mark gets help, I hope Mark doesn't hurt himself". I definitely feel that way too.
But what sadly gets lost in all that is the physical harm Mark has already done and could potentially do again to other people - like beating up his girlfriend (domestic violence is just as serious as mental illness), and knocking out his Cousin. What if he does something worse next time?