Guys, thank you for the suggestions. A few points here:
1. Worldnomads in fact sell Bupa’s insurance. I’d reckon it unlikely that Bupa covers something that Worldnomads don’t, and vice versa. Therefore it probably would be worth an effort to get positive statement from Bupa as to whether or not they cover third party damage for skydiving.
As an example, recently I had the same conversation with CareMed, a German insurer, and after several rounds of specific questioning they said that they don’t cover third party liability for skydiving, although it was not stated anywhere in their policy wording.
2. Generally for skydiving insurance, this answer that you got from Worldnomads
“You must be with a professional, qualified and licensed guide, instructor or operator”
makes me wonder: if we are on a jump with one or a few sports or fun jumpers holding USPA or other national licenses, neither of whom is a professional, “guide”, instructor, or operator, it doesn’t fit the wording. What do they really cover, then? Tandems?
3. It was (still is) an expressly stated requirement in some places that in order to jump there one had to have insurance covering the third party liability/ damage in a specific amount, so I used Worldnomads dozens of times, with their declared amount for such coverage being EUR 1,750,000 in the “Explorer” plan. Quite a few people did, too. Wondering, since when do Worldnomads exclude this coverage for skydiving? Since recently, or did they just forget to mention it since the beginning, and we were lucky not to discover it in some other way?
Overall, Worldnomads, Bupa, or CareMed do not look like straightforward reliable solutions, I guess we need to keep looking.