Let's be honest here. The IPv6 transition has failed. That was basically the gist of Geoff Huston's talk. That leaves two alternatives:
1. The transition was impossible. Nobody could have possibly done it correctly.
2. The transition plan was bungled. The Right Thing was a Wrong Thing. Or possibly, there were other Right Things that should have been done.
Ad hominem attacks against DJB-- or anyone else for that matter-- don't prove anything.
I tend to lean towards position #2. This is because I've read of other successful technological transitions-- even major ones! Some good examples are x86 -> x86_64, Apple's PPC -> x86 transition and DOS to Windows. Some examples of failed transitions are Commodore 64 to Commodore 128, x86 to Itanium, and the Apple ][ to the Apple III.
The failed transitions all have something in common: the people in charge underestimated the importance of having a transition plan. Compatibility was for little minds, people who couldn't see the big picture, the Right Thing. Itanium was so much better than x86 that its architectural superiority would crush x86 by sheer force. The fact that it ran legacy apps at a slug-like speed was irrelevant.
The successful transitions always involved a "no regressions" philosophy where existing setups would continue to work just as well, or possibly better, after being upgraded. Engineers often spent months or years working around bugs that had nothing to do with the new stuff, and everything to do with the mistakes of the past. For example, in one OS upgrade, Microsoft wrote special-case code that only triggered if the program was named simcity.exe, to work around bugs in that program that the old OS had not exposed. When new security features in its OS put additional burdens on application developers, those burdens were added gradually rather than all at once. Upgrading was made mandatory rather than optional by shipping the new version on all new machines.
Of course, you're free to disagree with me and insist that IP is fundamentally different than the other transitions described above. But at least give reasons.