In general, during competition, it's illegal to increase surface (i.e. dull) your equipment, but it's legal to decrease surface (i.e. polish).
For example, Neo-Tac's Renew-It, a mild polish, is acceptable for use during competition, but (according to the back label on the bottle) Liquid Sandpaper may only be used before or after.
So yes, I basically agree with your high-rev friend.
In this day of people bringing 8-12 balls to a tournament, this rule needs to go away. If Joe rich guy is allowed to use a dozen V2's, each prepared with a slightly different surface, then Tom poor guy should be allowed to adjust the surface of the only ball he owns.
After all, unlike golf, bowling is supposed to be a poor man's game, right?
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seadrive
Cogito ergo bowl