Surely every student has been in the situation where they wanted to say something to a teacher that would be seen as inappropriate. Some go ahead and use all the bottled up emotion on their teachers while others keep it in. Those who maintain themselves realize that their future could depend on the person they just blew up on. After the situation as a student you still need that letter of recommendation or that .01% to get the A. It is not being submissive, it is being clever.