Yeah... but given the results..
Results: There was no evidence that controlling for age, natal-sex differences in running performance are lower among non-binary athletes. Natal-male non-binary athletes outperform natal-female non-binary athletes at a confidence level of p=0.1%.
How can they conclude that gender identty is a useful explanatory variable?? or that there is any value in including gender identity as a variable.
Conclusions Both natal sex and gender identity may be useful explanatory variables for the performance of athletes in mass-participation races. It is, therefore, valuable to include both variables in data collection.
To me.. it seems an illogical conclusion based on the results.