Bernice can't be lumped in with Vienna or even K9. The situation is completely different.
I have little doubt that in 1999 you can probably find Gary Russell saying such a thing, because this is before the get the license to make DW. (By that I mean that Treasures is released in 1999, but likely made as early as 1998, or at least a point in 1999 before they inked the BBC deal.)
You can make an argument that the audios of series 1 were indeed produced with the notion that they weren't part of the DWU. But once you hit The Extinction Event, there's Irving Braxiatel, ultimately derived from City of Death. And by series 3, all of a sudden she's much, much more hooked into the DW universe. Her status as an ex-companion is more heavily featured. Daleks and Monoids and Ice Warriors and the whole DWU toy box is opened. And this new age is pretty much announced by the obvious title pun that starts off series 3: The Greatest Shop in the Galaxy.
Then of course you've got Benny showing up in a variety of BF stories that are firmly part of the DWU. The Excelis Saga can't be finished without Benny's The Plague Herds of Excelis — now marketed by Big Finish as a part of series 3.
There's no doubt that once they got the broader DW license they very firmly wanted her to be thought of as a part of the DWU. After all, Big Finish's entire aim with Benny was to create a portfolio that they could take to the BBC and win the Doctor Who license with. Without those early series of Benny, there would be no Doctor Who at Big Finish.
If you really listen to Benny after series 3 starts, it's pretty chock full of unambiguous Doctor Who references. It's not at all like K9 where there are just no clear references to the DWU, and the established DWU is often contradicted. Nor is it like Vienna, where Big Finish are clearly in the position to make it a DWU series, but have explicitly decided to go in a different direction.
So the question becomes not "what do we do about Benny as a whole", but rather just "what do we do about the first series"? And here I think there is some room for debate, because series one is comprised solely of adaptations of novels.
Our current Target novelisation policy is that if the novelisation contradicts the serial, the novelisation is deemed to be incorrect. You wouldn't throw away the whole novelisation, of course, because most of it is similar to the original. But with the first series of Benny audios, I think you have to take a firmer line. Because the author has removed major characters which they can't legally use in their derivative work, then that work should be excluded from the wiki.
Thus Birthright (audio story) and Just War (audio story) should probably be wholly removed from the wiki, since they originally starred the Doctor, Ace, Chris, and/or Roz in novel form, but do not have any of these major characters in audio. The differences between the novel and audio are huge, when it comes to writing articles on this wiki. We can't even assert with confidence who performed most of the major actions in the narratives. In the book it might be the Doctor; in the audio it might be Benny. And we're talking about nearly every scene having a different set of characters.
These accounts are in fundamental conflict with each other, and the audio version, as very much the secondary version, should be banished.