Is this IPv6-link-local address (as reported by Windows) correct? If so, why?

It's not that a link-local address is required to be generated from the MAC address; it never has been a requirement. You can manually assign link-local addresses on many devices.

What you are seeing with Windows is the use of Privacy Extensions and random addressing. Instead of the original way of assigning a SLAAC Interface ID, Privacy Extensions and random address generation were introduced. This is the default for Windows, but it can be disabled.

See RFC 4862, IPv6 Stateless Address Autoconfiguration and RFC 4941, Privacy Extensions for Stateless Address Autoconfiguration in IPv6.