Shawn, each of our views is correct. The differences occur in the definition of the AFM. I am more familiar with the UK CAA manual than the FAA AFM, but I have written and worked with both, although several years ago.
The UK view was that the AFM was the legal document to the extent that not even an inspector could over-ride it without higher approval. The manufacturer’s ops manual (FCOM) gave additional operating information, which often duplicated the AFM information to retain clarity. More recently, some European countries have dispensed with a separate AFM and only use the FCOM, but I do not know how the AFM (legal) content is identified within the FCOM. This could be a further source of confusion.
The FAA AFM tended towards the combined European manual, which included the type data sheet (mandated material) and the manufacturer’s recommendations. A local inspector could approve a change to the latter information. Thus, there was an opportunity for a representative of the regulator to overrule the manufacturer with obvious safety implications. I spent considerable time heading off many potential trouble spots.
I total agree with your last statement.
“Unless specifically authorised, everything else is prohibited”; attributed to the French certification philosophy.