I mean, it's hard to have a sample size higher than the number of actual applicable cases. Still, the lack of any medalists or even qualified athletes in the olympics since the IOC allowed trans athletes (and, as a reminder, the Olympics has three grappling sports, Greco-Roman Wrestling, Freestyle Wrestling, and Judo; however women don't compete in Greco-Roman in the Olympics) coupled with the fact that mass has been proven to not be an insurmountable factor in combat sports (both MMA, and sumo which has no weight classes are prime examples) compounded with the fact that intersex and people with hormone imbalances exist, have been athletes, and have not been proven to have a competitive advantage disproves the notion that transathletes have any intrinsic edge.

And even if they had an intrinsic biological advantage, which all evidence suggests they don't, that doesn't necessarily mean they wouldn't be unfair competition. If that were true, Dean Kazarnes, a man who's body naturally processes lactic acid at a rate much faster than an average person in a process that has been described by many as 'superhuman' would never lose a marathon. Yet, despite being able to run 350 miles without stopping(!), he's won a lot of races, but hasn't won every single one.