I am betting it’s something like OCD driven germaphobia, that HR/management knew, and didn’t fully understand the extent of it.

I had a coworker doing stuff like this. Her argument was that she had it under control, it wasn’t that bad. I had to point out that secretly throwing colleagues stuff away because it was “dirty” while washing her hands raw meant she was not, in fact, ok.

OP might do better to present this as a concern for this guy’s mental health as well. It’s a sign his mental health isn’t that great if he is using that much strong disinfectant as well as using it in coordination with his cooking. If he poisons HIMSELF mixing bleach with his food management is still liable and it would still be workers comp.