Was there really a pattern of erratic behavior, though? He was able to manage his finances, makes his dates and coordinate scheduling with the WWE. That event where he no showed was a cause for concern because he NEVER did that. No one has come out and mentioned any issues with remembering spots or other memory issues you'd expect with CTE. Hell, even Foley and Tommy Dreamer admit to having lapses.
People always say "oh his brain", but there was no documented pattern of behavior as a result. There rumors of abuse, but that just makes him a volatile piece of shyt like millions of others, not someone with brain damage.
The irony is that Chris is his number one defender, but has also told stories, seemingly unaware that they make Benoit out to be a dude who was a little off from day 1.
Look at the timeline. Murdered Nancy, probably in a rage. Sat on it for 24 hours before consciously choosing to murder his soon too.
From what I gather yes, apparently he got overly paranoid and more withdrawn, apparently he would make out 30 different routes even to a local gym. He also seemed to be dealing with extreme emotional trauma due to having many bereavements, from what have gathered it seems to be a combination of factors, the brain damage, drug issues, trauma (which can effect brain too), depression etc. Some close to him also noted a change, it unfortunately seemed like he was trying to cover it and some may not notice but in hindsight seemed to be some weird things going on with him.
But ultimately I don't know, I don't think any of us really do definitively and conclusively, that's why I can understand people that knew him and felt this was COMPLETELY out of character for him not to condemn him fully, as they probably think something else was going on and he wasn't in his right mind, they had those personal relationships and experiences with him to know him, nearly everybody says he's the last person they'd expect to have done this, so it must be shocking, traumatic and confusing for them, so I can't really be too critical on them not wanting to fully condemn a close friend some knew for decades when they think he may have had brain damage and wasn't in control of himself during that time.
Unfortunately we may not ever fully know what happened or the full causes behind it, but it's certainly a tragic terrible situation, for everyone who was family/friends of theirs