I'm not a lawyer, but having two opposite interpretations with no changes in the FARs in-between leaves zero interpretation. I understand someone has already requested additional clarification. That takes years to get. Considering this is STANDARD PRACTICE, the first letter is and will be considered to be correct. In a real legal battle, should one arise, these FAA-legal letters are just the first step.
He has already contacted the factory and they also agreed that he was taught incorrectly and there is nothing to worry about.
BRCC, I guess you're not going to correct you're teachers????????? Absolutely shameful! You're class should be audited by the FAA.