What a neat thread!
We're not Medieval "Schoolmen" who thought all the answers were found in books! We live after Francis Bacon (died 1626). He taught the world that sometimes you just go ahead and do the experiment. In this case, that means getting a cheap cue and buying a plane at a hardware store and shaving down the one side of the grip. Does it help your stroke? What happens to the tip?
By the way, whole bunches of famous players ROLL the cue in their grip hand.
On the subject of rules, I don't know about the rule for US pool, but Johann Scherz, from Austria, always played in billiard tournaments with a cue that had numerous bumps on it so that he could find the right spot on the butt and grip more securely.
Someone with some carpentry skills, please do this experiment and let us know what you find out!
But be careful. Francis Bacon died of pneumonia which he contracted when trying to find out what happens when you freeze a chicken.