Based on your first paragraph I can see why you weren’t convincing. Just admit that men are more capable at sports than women on average. That doesn’t mean men and women are not equal. Women can certainly do some things better than men. Gender equality is about equal rights and privileges. It doesn’t mean equally capable at everything.
When you said “gender-equality” those straight men understood you to mean equally good at things. Just clarify what you mean (i.e. equal rights) and you would have probably quickly found agreement.
I hope your youthful experiment taught you the problem wasn’t with the straight men, but with the argument you were making. Now I’m interested to know why your argument apparently worked with gay men.
I share your concern about how the bills keep coming. In fact, it’s likely the backlash will reach the national legislature at some point and a bill will be introduced there which is constitutional but restricts trans-girls access to joining the “correct” teams.
Reasonable people are not making the argument that it is “impossible for a cis girl to defeat a trans girl”. They are making an argument that being in a different sexual/biological category will, on average, have an advantage. You’re creating a strawman argument, which is another reason you may find it hard to reach agreements.
The generalization about men being “stronger” physically is true. I don’t know what science you found on Google, but for everyone you cite, I will cite ten that show you are wrong. On average men are stronger physically than women. And, more importantly for sports, the outliers at the top are extremely skewed towards being men. Serena Williams herself has said she would not even be ranked if she had to compete against men.
Yes, I can tell you that statistically, if I know an elite athlete is a transwoman I can accurately predict that she is more likely to be competitive against ciswoman in sports where strength, height, and other male physical traits are an advantage. You’re correct for some sport. For example, synchronized swimming does not give transwoman any advantage.
The dearth of transwomen in the WNBA does not prove your point. There are far fewer transwomen trying to make the teams and that is not federally funded, so they can be rejected before they start. You obviously skipped statistics classes in order to focus on gender-studies.
Most people who oppose trans girls in girls' sports don’t think they are freakish. Here you are using hyperbole to further alienate the people you should be trying to win over. (You really haven’t learned much about being persuasive since your youth). The main thrust of the counter-argument is about fairness and access to scholarships. They would use the same argument for doping. Unfair advantage.
And, girls are not being told they are inferior to boys. They don’t need to be told that obviously the boys tend to be stronger. Boys are told they can never have babies. We all survive understanding the realities of biology.
Finally, you make a thoughtful argument about reinforcing the binary. Here you make the case for not having gendered sports at all. How about a basketball league for people under six feet, regardless of gender? How about we give a gold medal to the first uterus to cross the finish line just like we do for the first one over 65 years old?
In the long run, many woman’s sports will become dominated by transwomen. Transwomen will hold all the records and get all the scholarships. It is already the case in many sports. Imagine the situation in another decade. This will do more to diminish the self-esteem of girls than an understanding of the reality that being born male is more likely to make a person stronger.
I’m not a fan of TERFs, but I am just as opposed to the trans-activists like you that are equally guilty of fomenting the culture war. I know a lot of transwomen and to a person, they agree with me about transwomen is women's sports. Some prominent transwomen do as well.
I know it is sad to tell a trans girl that she can not be on the girls' track team, but how is this any more sad than telling the short boy he can’t be on the high-school basketball team?
Male events should really be open events. Then we can have all the other categories we want. One of which should be natal girls after the age of puberty. Another can be short kids. Weight limits. And so on. (Prepubescent kids should all play together).
You’re still making a losing argument, so it’d be better to start having an honest dialog with the vast majority who disagree with you or you are going to create a backlash against the very people you purport to be advocating for.