I mean, it sounds like you have pretty much all the relevant information already?
strcat's technical chops were AFAIK never in question, but he had a tendency to pick up loud internet fights - to be fair, sometimes the other party were also being hostile jerks, but sometimes they weren't and he'd just swing at shadows.
After he pissed off Rossmann, he either realized or someone close to him made him realize (doesn't really matter which) that he should step away from the public square, and he did. Now he's just an ordinary, and I presume highly valued, contributor to GrapheneOS and to upstream AOSP.
Whether he still lurks the GrapheneOS discussion threads or not, or whether he is currently undergoing therapy or just chilling with a good book isn't really anyone else's business.
What else do you need to know?