It did work, but it was no where near as effective as if it was released at the correct time. It was released shortly before mating season so the rabbit kits apparently gained immunity.
So I went looking. The language is more considered. it tends more to 'unplanned accidental release' than 'guy goes off-piste and carries virus out the door bypassing security'
But.. maybe you can dig harder?
I predict that this second release will unwind even worst consequences that they will endure, while saying they couldn't have predicted it.
If you let a child play baseball in a museum, you can predict something will go wrong. That doen't mean you can say which statue or painting is going to be destroyed, or in what way.
This is also a country which wants to eradicate rats, possums, stoats, feral cats, and several other predators by 2050. See New Zealand aims to become predator-free by 2050 , linked to from this article.
See also "The Big Kill - New Zealand’s crusade to rid itself of mammals." https://www.newyorker.com/magazine/2014/12/22/big-kill ("mammals" here does not mean "all mammals").
Many Australian species are dying out because simply terrible at being animals. (It's not a matter of being overspecialized, because imported generalists like rats, mice and cats are outcompeting the native animals even in their specialized niches. They're just ineffective at surviving and reproducing.)
Also, if introduced/invasive species taking over a region is "evolution" etc, then the virus will just be another invasive species and the rabbits will have to face the consequences of evolution