There's a difference between what I personally find acceptable with regards to excluding trans folk from sports, and what I think is a realistic scenario with regards to trans folk participating in sports. In short, I think the hypothetical is a complete fabrication and not supported by what actually happens in reality.
And, just to be clear: exceptions will always exist. In that event, they should be actioned on a case by case basis, instead of trying to gotcha the general participation of trans folk in (competitive) sports based on the hypothetical of someone competing on the grounds of self-ID alone.
Would you be happy with me suggesting that all men should be banned from sports forever, because a minor percentage of men have tried to break the rules in the past? I'd like to think the answer is "of course not", which should in turn inform you and anyone else why people after 64 pages are kinda rolling their eyes at "but what if this completely unrealistic thing happened".
Look, as was pointed out in that article you reacted to so painfully for some reason, there are currently about 10,000 males, whose personal 100m sprint time is better than the current female Olympic gold medalist.
Considering existing incentives and the fact that professional athletes have been known to cheat in any way imaginable, including by risking their health and committing actual felonies to improve their results/placement (just ask WADA) I would bet my left testicle that several from among those 10,000 would compete as women in a heartbeat, if there were no rules in place from stopping that from happening.
Now may be a good time to remind you that I have not once in this thread taken a position as to whether we need
those rules - i.e. whether a hypothetical situation where cis-women can be eliminated from top positions in sport is a problem
This is because I admittedly am on the fence on this issue.
I can understand the argument advanced by @schlaufuchs
and others, that it can be seen as comparable to having tall, or rich, or ethnic group X dominate, hence not a problem.
It is also not for me to decide, as I am neither cis- nor trans woman, nor a sport judge.
I also despise professional sports, which for me represents mainly human trafficking, matchfixing, doping, hooliganism, institutionalized corruption, child abuse, wastefulness and vanity projects of dictators, so "fairness in sports" is not highly ranked among my concerns anyway.
On the other hand, I understand why cis-woman athletes would oppose this.
So, on the fence, but leaning towards the solution where at least some sort of actual medical transition would be required to qualify.