Wirbelsturm
I have had bags turn up late on a couple of ST flights with BA (I use it alot!). The bags have always been delivered, albeit late, and I have never had a claim refused/not refunded.
Likewise, similar has happened to me twice in the last 10 years ( FWIW less than 1% of my ST flights). On both occasions I was on standby travel and even so the bags were delivered by courier/cab the next day.
Like you and others I suspect there's more to this than outlined in the initial post.