The article isn’t about pure time, it’s about overall endurance over time. Women tend to finish ultramarathons at a higher rate than men, but not typically faster than men.
So to answers the OP's question: the reason she's the first woman to finish isn't necessarily because of bias or sexism, but could rather be simply because of the very challenging time limit, and the fact that the women's world record ultra times are around 10-15% slower than the men's on all distances from 50k up to 6 days (source: https://en.wikipedia.org/wiki/Ultramarathon)
