You should have asked this person to do the exercise while having the manual in front of them. Perhaps they might have made the same mistake? Regardless, your

You should have asked this person to do the exercise while having the manual in front of them. Perhaps they might have made the same mistake? Regardless, your test was specifically to confirm your bias that the mnemonic is enough to make a correct decision. There have been plenty of discussions about people blindly following authority. Can you really not imagine someone reading the entry and going "ah, that's weird... But ok"?