To thumb your nose at someone means to openly display contempt or lack of respect, which is the opposite of what the context is telling you to do.
Consider the staetement "Don't show your contempt openly towards the boss if you want to keep your job and get a better rating!". Based on this statement, is "Don't thumb your nose at the boss if you want to keep your job and get a better rating!" a true statement? Yes/no/unknown