Is this the best argument they can manage? Toby Young really doesn't have a clue.
For instance, if you plot statistical distributions for men and women with respect to where they fall on the systematising-empathising axis, there will be considerable overlap between the two.
So there is no such thing as a male or female brain, but there may be traits which are more common in men than women, or vice versa.
But instead of this obvious conclusion, he decides instead that
Trans activists could look at the research evidence and claim that people with gender dysphoria were, in some meaningful, biological sense, born in the wrong bodies — and many of them do make exactly that claim.
Transgender ideology relies on there being distinct male and female brains. The large overlap between the sexes is an argument against transgender ideology, not for it.