To clarify, the pictured poster Caroline Kwan is an ally, not a TERF. The TERFs referred to in the title are the ones ‘protecting a very specific idea of what a woman is’
Realistically it probably depends on the sport. Y chromosomes, being exposed to certain levels of testosterone in utero (unless one is resistant or unresponsive to the hormone), being exposed to certain levels of testosterone in puberty and maintaining certain levels of testosterone all do things to the body than could effect performance and that's all still mostly just focused on the one hormone. How much each of those things has an impact (if any) is going to depend entirely on the nature of the sport in question.
While sensible, is T really the only factor at play here? Once you get into the science where do you draw the line?
Realistically it probably depends on the sport. Y chromosomes, being exposed to certain levels of testosterone in utero (unless one is resistant or unresponsive to the hormone), being exposed to certain levels of testosterone in puberty and maintaining certain levels of testosterone all do things to the body than could effect performance and that's all still mostly just focused on the one hormone. How much each of those things has an impact (if any) is going to depend entirely on the nature of the sport in question.