Most of the times you hear people complaining about Hetzner shutting down someone's servers, it's because they were hosting content going against their ToC or similar.
But this seems to be about Kiwix (which in short is "offline Wikipedia" in various ways) and doesn't seem to be about questionable content in any way.
Eventually I guess we'll get Hetzner's perspective on this, as they tend to start writing publicly about issues once the other side starts writing publicly about it as well.
Personally I've been a happy user of Hetzner for many years, with no issues that weren't my own doing. But reading about people having their servers deleted in the middle of the night on a Sunday (Berlin time) and all data wiped immediately, with no recurse, does sound a bit aggressive. Luckily it seems like both me and Kiwix has mirrors for the data we care about.