Wow, it works, but it really seems like it shouldn't. I'd expected reserved domain names to not resolve at all let alone be pingable and point at a working webserver. Has it always had a website?

Yes, it’s always existed. It actually belongs to the IANA and if you Whois it you get: RESERVED-Internet Assigned Numbers Authority

If they're running a mail server too I'm guilty of sending them a lot of spam. [email protected] is what I've always used for people unnecessarily requesting an email addresses

Probably drops everything