Originally Posted by linglingfool

Weather is considered an extraordinary circumstance under EC 261, meaning airlines do not have to pay compensation when that is the cause of the delay/cancellation. Credible security information regarding a specific flight is something that happens on a very, very small percentage of flights, and is an occurrence that would be judged by most to be "extraordinary" -- agreeing with your logic doesn't change that.

However, I'm still not sure what is meant by a "security sweep" by the OP. Even if it did entail a sweep of the plane by police, I would personally still claim compensation, as there's nothing to lose by doing so. Even if they deny your claim for cash, they may throw a voucher or some miles your way.