I'm thinking of shorting the tip on my bill because the service staff assumed I was someone's mother.
That sounds extreme. Tell me again why you want to short your tip?
My waiter is an arrogant prick who thinks he's God's gift to the world.
If someone thought that you were a parent, it isn't a serious social faux pas that should result in his or her tip shorted. Service staff depends on tipping to make a livable wage and shorting a tip should only be done if there was a serious breach in the service quality received. Making the assumption that you are a parent has no ill intent behind it and therefore your waiter should not be punished for making that mistake.
If I don't tip, maybe my waiter can learn a lesson.
Sometimes people make honest mistakes and I don't think he meant any offense. It is important to tip waiters unless something really bad goes wrong.