HM,
That's right. The reasons you give are the rational for the different language used for weather and strikes.
From the beginning delays/cancellations extraordinary circumstances defence only applied to the specific flight(s), it wasn't a ECJ interpretation.
The glorious EU have been prevented from bringing a redrafted regulation which, amongst other things, defines extraordinary circumstances due to the intransigence of two member states who can't agree on a rock sticking into the Mediterranean.