I feel that his abrupt choice to self-isolate (so unusual that his Mom reported him missing a month ago), particularly when socialization was a large component of his life before, would itself be indicative of some kind of mental issue, be it organic (schizophrenia, brain tumor, etc) or self-induced (hallucinogenics, etc). I feel like we would be getting more of the typical 'he was an odd duck but a good dude otherwise' stories from his friends and family had this type of behavior been present in some form or fashion prior to something happening to him.
I am not advocating or condoning a political view one way or the other here, but to your point I suppose something as simple as an election result could trigger an otherwise normal person to lose most contact with reality, if briefly. And as staunch as he was in his views, and with his views seemingly not aligned with the incoming administration, I suppose something like that could have even set him off on a path like this. He disappeared around the same time as the election (if we assume his mother's missing person's report as the 'when' it began unraveling for him).
JMO.