A serious incident is not the same as stubbing your toe. If people do not get out in time then they die... understand that airline profit is important, but really?

Anyway you missed the point. The issue is not with removing the flight attendant per se, but with meeting the standard evacuation time in a consistent, objective test. Statements like "who cares if it takes 15 seconds longer" are silly, because the test standard was developed for a reason. If you pass the test then fine, if not then not fine (unless you are in Canada or similar places where you can repeat the test as often as you like and bend the rules if you need to).

I am not sure what constructive input the union rep could possibly have had during the test, but on the other hand specifically prohibiting him from attending gives the impression that someone believes that the Sunwing fiasco will need to be repeated and they fewer witnesses the better.