You have made a number of the same incorrect assumptions that all transphobes make.
1. "I am against it in competitive sports where the physiology does matter". - You ignore the real issues, which are: (1) the extent to which physiology matters more than human decency; and (2) the extent to which ALL of the relevant factors and not just the ones you pick and choose weigh against each other. You ignore that there is a lot more to a child's soccer prowess than physiology. You completely ignore the emotional and other factors where trans children are placed at a huge disadvantage. You also ignore that no trans girl in history has even ever been the best player on their own team. The fact that you won't even attempt to weigh the disadvantages that a trans child has with the purported "advantages" they have physiologically is also very telling. Of course you won't, because like all other transphobes, you can't even acknowledge the humanity of trans children. It is crazy that you see being trans as all "advantages", but the reality is that is a transphobic pathetic piece of shit point of view. If you were serious about any of this, you would acknowledge there are also massive disadvantages for a trans child playing sports, but you won't, because you know the end result of actually weighing all the relevant factors is that me, ECNL, CIF, the NCAA and a majority of the even the most conservative freakin' US Supreme Court since slavery was legal agrees with me.
2. "You choosing not to believe it, does not make it untrue." - This is a fake bs argument that you and your friends keep making, and must keep making, to rationalize that actual fact that you are choosing not to believe any of the important disadvantages that trans children face that offset any physiological advantages. I have said here, for example, at least 10x that I was not a fan of the NCAA's swim rules and I have no problem with changing the rules based on what happened with Ms. Thomas. The reality here is that I actually do weigh all the factors, and my position is actually pretty middle of the road. The only ones here who choose not to believe that any justifications on the other side should even be considered come from the transphobic side that includes you.
3. "That does not mean I am anti Trans." - The fact that you refuse to weigh any of the disadvantages that trans children face in sports, the fact that you can only perceive a purported physical advantage despite no evidence whatsoever that any trans girl has ever been even the best player on her own team, rather definitively shows that you are anti-trans. The fact that you completely ignore that awful transphobic commentary by your compadres without any criticism whatsoever, but instead go after someone who (as I stated earlier) agrees with ECNL, CIF, the NCAA and a majority of the US Supreme Court, is also pretty anti-trans.
4. Trans participation "infringes on the opportunities of others." That is ridiculous with respect to kiddie or even NCAA soccer. You can't point to a single instance in which the result of a single game was ever changed because a trans girl participated in comp soccer. You can't point to a single instance in which a biological girl lost out on a scholarship or a college offer because of a trans girl, because it has never happened. You can only claim that a trans girl playing in a game must have meant that a non-trans girl lost some minutes. But that also ignores that she lost minutes because of 10x as many cis girls on her team.