A member tattled on a coach

Why would a member want to tattle on a coach? One of the new TRX exercises, was awkward. The first time we did it in class our coach gave us an option. We had the same move in our class today and the coach told us he got in trouble with his boss because someone said that he gave an optional exercise. I love this coach , and he does the best for everyone in class. Why would he get in trouble for giving an optional exercise?