Everybody I know is happy with what Hetzner provides, even at production level. OTOH, "arguably better" DigitalOcean sent me a "Your physical host died, so we restarted it. If it persists, we'll migrate" e-mail, which just shows the reality of the hardware.
On your question, while I do not have services on Hetzner yet, I manage a lot of servers, so I know dynamics of a datacenter and what it entails to keep one up.
Your beef is not with Hetzner, but whoever decided to run the service. Unless the customer violates local legislation or the hosting providers ToS, the appropriate action is to leave the service running, be it AWS, GCP or Hetzner.
I would quite frankly have been very disappointed with them if they had done anything in response to you request.
Hetzner is German company and subject to German law. The website they were hosting did not have the (in Germany) mandatory legal notice (Impressum) or any contact details. This shifts the responsibility to the provider (Providerhaftung). Ignoring legal requirements is hardly professional.
Also I would like to note that I did neither request them to give me their customer's details nor to shut down the site. All I wanted was them to work with their customer to have the offending image removed.
Also I am convinced the porn image was not malice but an accident. The scraper replaced all profile images with ones they probably scraped from a forum. I was just unlucky to get a very indecent one.
Had Hetzner collaborated I'm pretty sure this could have been resolved in no time.
I get your frustration in the situation, but even if it would have been helpful to you, it would be extremely unprofessional for a hosting provider to invervene in the operations of its customers unless the customer violates the Terms of Service (an agreement you have no part in), a court order is made, or law enforcement makes a legally supported demand. Random legal notices sent by mail from strangers are not on this list, but could lead to Hetzner evaluating if a ToS violation is in effect that must be resolved.
If the customer is a business, it could be that they have breached the Impressum laws. It would have helped you if they had the impressum, but until legal action is taken it remains undecided if there is a violation, and if there was the consequence would be that the customer is liable for a written warning and in some cases a fine, as decided by the relevant authorities or a court of law.
Nothing that would involve you as a third-party individual.
It's highly available though and the redundant replicas run on their separated physical machines
https://docs.hetzner.com/cloud/placement-groups/overview/
Single machines die (and can't be started again for a few minutes to hours) every few months, but that's acceptable for me, and we also similar things happen at AWS.