The scenario I was comparing is an underage kid visiting this website, generating an ID, and accessing content that would otherwise be illegal for them to access by using the fake ID. In this scenario, everyone (potentially) would be in trouble, not just the website verifying the ID, just like an underage kid buying smokes with a fake ID.

The reason I mentioned domain registration was not because it is illegal to register a domain or anything of that sort. I mentioned it because it suggests the website owner is based in the UK, which is easy pickings for the UK government to pursue (if they choose to). If the website owner was based in Malaysia, it would be significantly harder for the UK to pursue any legal recourse against them (if they choose to).