I think it's pretty clever, and demonstrates something very powerful about GitHub's position as de facto global code repository: you can get a strong cryptographic identity for (almost) anyone on the service, which you can then sign/encrypt to, verify for, etc.

age (another tool of Filippo's) leverages this to make encrypting to any GitHub user easy[1].

[1]: https://github.com/FiloSottile/age#encrypting-to-a-github-us...