I do not think this is how a hidden neo nazi would suddenly show their stripes after 30 years. (Real neo nazis don’t hide that well - they don’t feel they should have to).
I would think this is how a person with personal problems bursts out with the equivalent of f*** you. The onset of dementia or mental illness can sometimes look like this - or maybe an impending divorce.
He certainly shouldn’t be teaching until his need to provoke such upset in his students is gotten to the bottom of.
Edited to add that I think naming, specifically, hubris as a reason shows a very personal claim of responsibility. He could have left that one out without throwing a (hypothetical) TA under a bus. But he didn’t.