Does he do experimental work? Something that progresses so rapidly almost makes me think that a chemical used in work could be having an effect. Anything Heavy Metals (Lead, Mercury), that kind of thing.
I am near certain he is not a drug user either. I have never seen any evidence of this, and in my experience drug addicts are not very good at hiding it when they lose control.
Also, I contacted his work abbout his absense (without details) from my own phone. His colleague (boss?) called me back because they were already concerned about him late last week at work. If they suspected something concerning the work they do, they would have told me or the hospital.
Not sure if it's relevant, but psychedelics (mushrooms) broke a college friend after minimal recreational use. Like, maybe twice, with zero past history of any other controlled substance.
His delusions were similar to what you described. In hindsight, I wasn't qualified to handle his deeply troubled mind.
You did the right thing contacting family and seeking professional help.
If he harms himself, it's not your fault.
Addiction takes a lot of forms and its very likely you know people that are good at hiding it.
could it be possible though that prolonged exposure to chemicals excacerbated his preexisting conditions?