I can only echo what the others have said above; you have been given incorrect information.

Printing out a response from a Flying Blue agent and bringing it with you will not assist you; it is almost 100% certain that, if you show up in Amsterdam having skipped the first leg of your ticketed itinerary, it simply will not be possible to recover the ticket in time for you to board and travel as planned even if you meet a sympathetic agent who attempts to apply such a waiver to you.

Flying Blue's T&Cs are very clear that the no-show policy of the airline in question applies to Flying Blue tickets:



KLM's no-show policy is as follows (§3.4):


Even if you have conflicting advice in writing, I recommend that you ignore it. You will not be able to start your journey as currently booked in Amsterdam without significant additional expense, hassle and time. The check-in staff at AMS will be unable to deal with your query, as it relates to a Flying Blue ticket. They will advise you to contact Flying Blue. I am not at all sure that Flying Blue will be able to "help" at such short notice if you are only ringing up to fix this when you are already at the airport; you are almost certain NOT to catch the flight you are booked on, and whether you get to travel on a later flight will still probably depend on availability of award seats plus your ability to pay for a new ticket