Edit: previous 2 posts made as I was typing this. I echo Gertrude's sentiments.
Usual caveats of course - we weren't there, so don't actually know what was going on in the instructor's head.
If the instructor
really didn't know what to do when faced with an EFATO then most definitely find another one - you'll live longer.
But perhaps the instructor simply did nothing for half a second or so to see whether you were going to cope with the emergency, and was going to jump in if you got it wrong - and half a second would seem like an extremely long time in those circumstances!
(When you come to the test the examiner will do and say nothing in such circumstances, until he feels your lives are in danger. Coping with a real emergency is part of the test. Personally I feel that that's all very well, but I tell the examiner that if we have a fire in the air then sod the test, he is to take control immediately and try to get us down alive.)