MP
Sorry you had to learn it the hard way, but there is a big difference being being responsible for a flight and accountable for the conduct of the flight.
The former can be delegated and the latter cannot, as you found out to your cost.
I suffered from a similar assumption, except it was in reverse.
The instructor on my first night circuit for a year did not watch closely enough, because 'you seemed well in control and made a beautiful approach', however, I screwed the landing and was lucky not to damage the aeroplane as the instructor was too late intervening.
At the time, I had over 200 hours, was confident, knew the drills backwards and good on the r/t -BUT I was out of currency at night, even though very recent during daylight.
Moral of the story, if you are there as an instructor, monitor like a hawk and be ready to intervene at any stage.
If the person you are instructing doesn't like it, they have an attitude problem.