I don't think that would be a fix for the problem I'm talking about above. It seems that crooksandliars have fixed their IPv6 DNS now, so the site works fine on v6 now, as it did on v4, though they are still using an autogenerated address for the site, which I will continue to consider bad practice.

All that your command-line will do is disable IPv6 autoconfiguration, which can be very useful in many situations, such as on a LAN. Your suggestion could be useful if you are stuck behind a broken router which will silently drop AAAA queries for IPv6 addresses though.

Cheers,
Andrew.