I expect he quotes things like the Target survey (I think) from the US saying they found no problems with men in women’s spaces and other observational studies that ignore the fact that absence of evidence is not evidence of absence.
All those arguments start with the assumption that men’s desire to be in women’s spaces is a genuine rights claim, having never established a genuine need, nor having considered alternatives that don’t include invading women’s spaces.
If you argue the medical model (now well outdated) it was that these men are patients, who need to be in women’s spaces for their mental health. If that need was genuinely established, and there were no alternatives, then arguably you are looking at a genuine rights clash. That might require the balancing of rights between the number of women who would be negatively affected by men in their spaces against the genuine benefit those men gain.
So really, it’s a transactivist argument that starts out with the assumption that men have that right/need and it’s all about weighing their rights against women’s. Most of us refuse to cede that claim because moving those men into women’s spaces was never discussed and women’s needs weren’t even considered before it was done. Nor was there any consideration of alternative arrangements, which are the obvious choice, if those men really have a genuine need for spaces away from other men.
So he’s presumably moaning we won’t debate on his terms, which would involve us ceding women’s rights before we even start. It’s similar to those men who claimed we could have a debate, as long as we accepted TWAW as a starting point. Just no. We want all our rights as they were and if men want to argue they should have access, they need to present a convincing argument as to why and why genuine alternatives are unreasonable.
Unsurprisingly, they never want to start from there. They moved in without considering women at all. Our rights are assumed to be negotiable without ever having to put in the hard work of demonstrating why men should be admitted to women’s spaces at all.