And what the hell was up with swanning around with four stripes ? I believe if you have never commanded a commercial aircraft it’s not a valid thing to wear .
Thread drift, though yes, I agree. Four stripes, like "Doctor", or "P Eng" should be respected from being earned, and granted by peers.
As to the topic at hand, if the instructor (and I'm guilty of this) has waited too long before counseling, and then requiring, the candidate to correct, that's not the all candidate's fault. The instructor has to own that, probably with an apology after the "taking control" without a briefing.