There are literally thousands of female participants in marathons around the world every year, and you have to be in denial to ignore the obvious sex-based difference in performance.
For ultramarathons, in particular, the performance difference is smaller, but it still exists. The most you can claim is that at ~200 miles there's a slight average performance advantage in pace for women in specific studies.
https://www.nature.com/articles/s41598-026-46032-9?fromPaywa...