Certainly would be self defense, but:
She wasn't carrying a knife for self defense, and again it is a story that "somwhere a while back ,somebody defended themselves with a knife" which I am not doubting, just saying it probably is not going to be my priority when choosing a knife to EDC.
Not sure where you live that people are getting stabbed all the time. Stabbings happen fairly often in the city near me, but as an offensive occurence between crack-heads.
You never hear of an average Joe repelling an attack with their knife out on the street.