I hold a music degree and I'm probably a better engineer than you. :-P

Go look up the "#unqualifiedfortech" hashtag on Twitter for the prevailing viewpoint. Hint: no one in tech cares.

I don't see her music degree as an indicator of her (in)competence to do the job.

Anecdata example: my PhD is in neurobiology. Some of my engineering has been orbiting Mars since 1976. No neurons involved, just aerospace engineering.

The breach that occurred on her watch is definitive of her incompetence. Nothing to do with her degree.

Not directly comparable, but I've known economists who have a far better understanding of security risks than some computer scientists who have received teaching in the area.

The lack of a relevant degree isn't exactly a mark in her favour, but it's not a red flag either (especially this far into her career).

on it's own it doesn't mean anything either in favour or against her.

Lots of more experienced IT Security people don't have appropriate degrees, generally as they didn't exist when those people got into the profession.

As a personal data point, I've been in IT Security for 17 years, my degree is in accountancy :)