This applies mostly to the US, to a lesser extent to the UK, and to a much lesser extent (or not at all) to the dozen or so other Anglosphere countries.
But as we all know, the US is all that matters, so you may as well state outright that it “is so”, and move on.
This is an American news paper reporting on an American CEO of an American company...
I looked at guardian's style guide (british) and some australian style guide I found and they both default to "Ms". Which specific anglosphere country did you have in mind?