Re: "they weren't in use so nobody was affected"
"Yeah, as we said, doesn't speak well for IPv6 adoption."
Perhaps that was meant as a joke, but if not... IPv6 is intended to be sparse: the fact that a large number of unused addresses are not in use merely means those addresses are not in use. It says nothing about IPv6 uptake, or the number of addresses that are in use, or even the number of announced prefixes (either in general or within this block). This error will not have any impact on any conventionally announced addresses. If anything, it is a demonstration of how robust IPv6 can be in the face of such mistakes.