Hi Graham,
For what it's worth, I used to use Norton exclusively. I was a huge Norton Disk Doctor fan and I went on from there. They had one of the best names going in the business.
Then, some years ago, Norton stopped being friendly with my programs. They created all sorts of mischief on my computer. So I stopped using them. These days, like Mac, I use Avast. It's never created any issues for me.
I don't understand your logic in blaming PG Music. It seems to me that Norton should have had a pop up message that asked whether the program was legitimate. You are both a Norton user and a BIAB user. As a Norton user, the problem arose with a BIAB file. You have every right to contact Norton on this.
These days, I suspect that Norton is heavily geared to the Microsoft suite of programs and thus it doesn't readily accommodate software outside of this.
Good luck with your problem.
Noel