Never in my 20 years of programming, data engineering, engineering management of games, search engines, dating apps and machine learning systems I had a problem of people not wanting to hire me because I prefered Emacs (and linux).
The opposite is also true. I have never heard anyone climbing the ladder specifically because they are "so fucking good" with [insert whatever IDE/editor]
Dude is saying nonsense. "Emacs users are unemployable" sounds like "Tesla drivers unregisterable" - what an imbecilic, utter bullshit that has zero sense to say. Ever.
In fact, in was the opposite.
So what are you even talking about?