That is a good point.
The last actual evaluation of his mental capabilities was
12 years ago. at a time when Chris was still participating in society by going to school and doing other things.
But things since then have progressively gotten worse with him leaving college to become a shut-in, Bob passing away and the whole tomgirl era.
We know that there likely was an evaluation by a court appointed psychologist after the Gamestop incident, but that would have been more to check if he's a danger to others.
I would bet my bottom dollar that his mental health (and his ability participate in "normal" things like school or work) have since then declined quite a lot.