Well, you can claim ... The Jet2 judgement didn't say that all tech delays were subject to R261, just the one that occurred on that flight. While the criteria has obviously tightened each will have to be considered on its own merits. I can't think of any airline that will just roll over and pay all claims, including claims previously denied, that occurred up to six years ago.
Bird strikes are technical in nature, for example, but still considered extraordinary circumstances.