What does "wrong for good" mean in this context [closed]

The Hitchhikers Guide to the Galaxy has gone through many incarnations.

First it was a BBC Radio series, then a Stage Play in London, then a book, then a BBC TV series, then a film. Not to mention sequels. In each incarnation after the first, the story changed. Although many events and most of the characters are common to the variants, there are many changes.

Fans of the Guide tend to regard the version that they first encountered as the "true" version and all other versions are "wrong".

Douglas Adams always considered the story to be fluid and didn't worry about inconsistencies. Each incarnation stands in its own right.

Indeed, to quote from the script of the second radio series, episode "Fit the Tenth":

’The Hitch Hiker’s Guide to the Galaxy’ is an indispensable companion to all those who are keen to make sense of life in an infinitely complex and confusing universe.

For though it cannot hope to be useful or informative on all matters, it does make the reassuring claim that where it is inaccurate, it is at least definitively inaccurate. In cases of major discrepancy it is always reality that’s got it wrong.

So, in writing a piece in which he states things are "Wrong for good", he is just playing on his work being "definitively inaccurate" and "for good" indicates both lasting for ever and being a good thing. You just have to remember "it is always reality that's got it wrong".