(But if you're expecting to be frequently falling onto wet snow or hard ice, it's probably a good idea not to have a $1000 smartphone in your pocket...)
Learning to ski is certainly a particularly strong example of a case where you're likely to have a lot of false positives.
But, honestly, even with something like hiking, tripping over a tree root or something like that isn't exactly rare. I've taken a ton of spills over the years and fortunately nothing worse than some minor bloodshed or maybe a twisted something was involved. (And the one time it was something more serious I didn't actually fall but did have a serious bone break.)
I've been on the fence whether I ought to enable the feature on my watch.
If they got up and have started walking again, its a false positive, or they don't need automatic help.
Maybe Apple is delaying the fix because these news stories are viral marketing for its crash detection feature?