He has severe mental illness, or is on a drug of some kind. Could even be prescription.
If he is truly ill, with a large employer, I’m going to go against the flow here and say he shouldn’t be fired. Actually, I’ve had a close family member in the same situation, although he didn’t get naked.
What they will do is figure out why he did this. If it is illness, he will be treated, and they will take the doctors recommendation on whether he may return in some way. He will probably be reassigned to another job. If he is still too ill, then before he gets “laid off” they usually retire on disability. But the doctor may say he is too ill to return, which is what happened to my family member.
Snapping like this is often bipolar illness. They become delusional and irrational, and many do it in a way that gets a LOT of attention, because they can “go for it”.
If it is drugs, I don’t know what the system does. My guess is much more likely to get terminated.
Unless, of course, he's tenured.