Stupid advice does not get better by poorly associating Ben Franklin with it however. The original quote and for sure it has meaning here: “And now, to conclude, Experience keeps a dear school, but fools will learn in no other, as Poor Richard says, and scarce in that; for, it is true, we may give advice, but we cannot give conduct. However, remember this: They that will not be counseled cannot be helped; and further that, If you will not hear Reason, she will surely rap your knuckles, as Poor Richard says.” It is from Poor Richards Almanac - a fascinating book that has lost no relevance in 240 years...... The part about not hearing REASON applies to your situation quite adequately.
You of course could try to back up your premise. It won't be easy as too many have failed regardless of the air with which the advice was delivered. Corners up get a thumbs down. Embouchure advice without knowing anything about the player is even a bigger insult. It is always the missing context where the weak lose.