Hoping to get some help here with my currently denied Trip Delay issue.

Last year at the end of October I was planning to fly from London Stansted to Memmingen Germany. After arriving on time (3hrs ahead of time) at the Airport and just about to drop off my luggage Airport officials found a suspicious package and evacuated the airport. All passengers were forced to wait outside the airport for almost 6 hrs while the military detonated the package just to find nothing inside. In the meantime, my plane left without passengers (Ryanair) and there were no other flights in my direction the rest of the day.
Ryanair being a very bad airline, there was no help and after an additional 4hrs in line to get to speak to a rep, I was told to book a new flight for the next day and I'd be refunded later. I was handed a piece of paper with a complaint email address etc.
I left the airport that night to check into the Hampton Inn at the Airport since it was already extremely late and my new flight the next day would be super early.

I booked my initial flight and my "rescheduled" flight with my CSP thinking I could use the Trip Delay benefit to get the hotel cost and dinner covered.

When I returned I immediately filed a claim for my Trip Delay benefit, attaching all the documentation I had, an official response from Ryanair (+ their own website had the event covered) that said the flight left without passengers, media coverage and an official airport response that confirmed that the airport was closed during the time my flight was about to leave. Yet, my claim was denied last week as my reason wasn't deemed eligible. After calling eclaimsline, they were telling me that they deemed it ineligible as security not operating isn't covered.

Now no one here wants to take the blame and Ryanair says they haven't officially canceled the flight, hence no reimbursement saying it's the airports fault. The airport says it was a security incident, they don't take liability and as mentioned Eclaimsline says it's not covered.

Surely enough, I'd like to appeal this decision, but would love some opinions on this. I'd think that this would fall under "Hijacking" or terroristic act as per the Trip Delay terms, but happy to hear what others are thinking. I was told to write an email with the word "Appeal" in the subject line to appeal this claim, I wonder though if this is the kinda situation where I would need to send a letter through registered mail to get somewhere.

Thanks!