Thanks for the link. I am familiar with Regulation 261/2004 and will have the necessary documentation with me in case I need it.
I did get another response from KLM which said " I understand your concern about the flight. I have sent an inquiry to our higher management to check on the frequency of cancellation for flight KL621 (Amsterdam to Atlanta) and the cause. I regret as of the moment, we need to wait for a response. Kindly get back to us in 24 hours for us to check for an update."
I waited the 24 hours and sent another email; still waiting to hear back. At least my question has apparently been escalated to a higher level.