My personal views are that children and adults have the same equal standing and deserve equal respect, therefore I wouldn't say that "you should never speak to your parent or an adult like that". I think what your son did is inappropriate regardless of whether either or both parties was a child or adult. I would think the same if you were the one saying those things. It may seem a small point but showing that you are equal paves the way for conversations and understanding rather than you deciding on the rules and them just following. After all, as he grows into an adult he will have to make these decisions for himself and knowing the 'why' behind the 'what' will help him in this.
I hope this helps (and makes some kind of sense