Sometimes you make a decision in life that affects your future in a meaningful way. Becoming a trans is one of those things. Sadly there's no good solution to the problem it causes in sports right now so the only possible answer is to not have them in the competition.
They are not saying to leave them behind, and comparing this to not participating in life is an unfair exaggeration. The situation is far too complicated for that. It's not just about politics here, there's other people involved that would be put at a disadvantage, others that would abuse the situation to gain money, etc.
And yes, I'm well aware of the injustice being done to trans people on every possible level, and that needs to change, this battle itself though is just not the same.
*Edit: I'm reading further down that this "problem" it causes might not be as big as I heard it was in the media. So take this comment with that in mind if you will. It only proves the complexity of the issue though.