I say take it. He's a major league pitcher, he should be able to use the scouting reports, the pitches called by his coach/catcher, and his ability to control his pitches, and get batters out. And we don't need anything else to slow down this molasses paced game any further.
IMO, this is an over simplification of the rule. Throughout the book (well, 8 times) it refers to a foreign substance. The purpose of every point where this is mentioned refers to the application of some substance that will affect the ball during a pitch.
A cheat sheet does not meet the criteria to enforce the rule.
MTR, are you talking baseball or softball rules? Clearly in softball the USA rule book says "foreign substance upon the ball" Just curious if you were referring to softball or baseball with your response.
And in softball, for years, pitchers and other offense and defense players have been using the wrist bands with all the secret codes. It just can not be distracting to the batter if worn on the pitching arm.