However, nasa.gov DNS looks a bit odd.
Registrar is GoDaddy. I would have assumed that was not possible for .gov domains.
There is no A record for nasa.gov, but a slew of MX records (so the justification isn't in ancient, inflexible mail gateway config).
www.nasa.gov is a CNAME into Akamai (so they know how to do that).
There might be a valid reason why nasa.gov can't be used as the canonical web address, but the blog post explanation doesn't seem reasonable on the surface.