I autofilled the form with my browser and was unaware of the issue until I got their e-mail.

There was no chance to remedy this.

I understand that they have no legal obligation to me, and am posting to make others aware that the company might not be interested in resolving conflicts with anything other than the heaviest of hammers.

That Hetzner cannot be sued for this is different from claiming this is acceptable behavior.

Most people come from cultures where filling a form incorrectly does not entitle people to immediately destroy their things.

I also come from a country where putting "full name" on a form only means people expect more than your first name and it is customary to not use all of your last names. I am sure many are in the same boat.