I don't think this is necessarily cissexism... though it may feel like that. I don't have an answer on what to do on a sports by sports basis and I don't think the matter will be settled any time soon. There are strong positions on both sides, both by trans-women who want to be included and cis-women who will insist trans-women have a biological advantage. This applies more to some sports than to others.

You have taken a strong stance and for what it's worth I agree with you, the Kaufmann solution is a hedge and it suits nobody. I don't think that necessarily makes him transphobic. You've presented a binary argument. 'Either you support freedom for marginalised people or you don't.'

I do.... but you're self identifying the trans-community as the marginalised people under attack from the patriarchy here. Cis-women athletes are also identifying themselves as a marginalised group under attack from the patriarchy. Where does the centre ground rationalist Penguin position themselves? I will support freedom for any group of marginalised people but not at the cost of impinging on the freedoms of other people. When that happens, society needs to slow down and take a long and careful look at the problem, free from emotion on both sides.When there are competing groups with an equal claim to unfair treatment... we must tread carefully.

Why? Because if we don't tread carefully and allow the wheat and chaff arguments to sort themselves out, trans-women and cis-women are going to get in a long-form and acrimonious slanging match that isn't good for either group. Each group will simply double down on their initial bias and create more of a mess for everyone else to sort out. :o)