My take on the contention with trannies going into female sports is that it has very little to do with concerns about women "professional" athletes being dominated by biological males. Rather, it is mainly parents who just want their daughters to have enjoyable time competing in sports, and they see biological males ruining that enjoyment as they easily overtake any competition and make it a lopsided match, which is boring and no fun, especially for those who are on the losing end.
Most parents who watch their kids playing sports have a realistic understanding that their children are very unlikely to be competing at a professional level. They usually understand that a healthy competition builds character and gives them a good outlet to exercise and compete.
Having trannies come into female sports takes all that away, as it is well known that males are physically dominant in practically all sports.
@Mongoliaboo Yes, too many parents are either asleep at the wheel or are not allowed into the picture enough to make enough a difference (in other words, the fathers). I would hope that parents who have their children involved in sports would care about their overall wellbeing, which should include teaching their daughters not to slut around. But many parents also do not realize that it is a real problem to allow your daughter to be a slut or they are too naive to even consider the possibility.