Am I entitled to compensation after flight delay due to aircraft problem blamed on a "hidden defect"?

I had a flight recently from Helsinki to Bangkok with Finnair, that was delayed for almost 4 hours. From what I understood from the crew, there was something wrong with the fuel, and they had to remove all the fuel from the plane, and fill it up again.
According to Your Europe Air Passenger Rights, I'm entitled for 600 euro compensation (more than 3 hours delay, more than 3500km distance).
I contacted Finnair a few times, and after a month they replyed with this message:
According to the information we have received from Finnair Technical Department, the aircraft manufacturer has confirmed that there has been a hidden design defect in fuel quantity measurement in Airbus A350 fleet. Airbus informed of new modified software for fuel quantity measurement to be ready during year 2017.
Airbus has published a document (TFU number 28.25.00.034) of this hidden design defect and thus no compensation will be paid regarding this flight delay.
How is Airbus publishing some document related to my claim? Are they trying to blow me off, or are they right to deny my claim?
Pictures about "Am I entitled to compensation after flight delay due to aircraft problem blamed on a "hidden defect"?"



How long does a flight have to be delayed to get compensation?
If your flight's delayed for 3 or more hours You're entitled to get compensation if the flight arrives more than 3 hours late and it's the airline's fault - for example, if they didn't get enough bookings or there was a technical fault.Is my flight eligible for compensation?
Claiming Compensation for Flight Delays and Cancellations Delayed flights: you may be able to claim compensation if your flight arrived 3 hours or more late. Cancelled flights: you may be eligible for compensation if your flight was cancelled less than 14 days before it was due to depart.What counts as extraordinary circumstances?
What Are Extraordinary Circumstances?- Acts of terrorism or sabotage.
- Security risks.
- Extreme weather conditions e.g. volcanic ash cloud.
- Political or civil unrest.
- Hidden manufacturing defects.
- Industrial action (strikes unrelated to the airline such as baggage handlers or air traffic control)
How do you get compensated for a delayed flight?
There are no federal laws requiring airlines to provide passengers with money or other compensation when their flights are delayed. Each airline has its own policies about what it will do for delayed passengers. If your flight is experiencing a long delay, ask airline staff if they will pay for meals or a hotel room.Am I entitled to compensation for a delayed flight?
Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.
Images: Julia Volk, Bob Ward, MART PRODUCTION, Jeffry Surianto