The physical differences exist today and are exhibited based on biological genders. That does not preclude that these differences are unduly influenced by environmental issues (including socialization). However denying that they exist (which is what Cahill is objecting to here) on the basis that the cause might be environmental and not "innate" just means that the ability to understand and treat neurological disorders in females decreases.
The reality is that there are differences. The cause of that reality can be complicated and nuanced and not inescapable. but as the change in societal standards is quite slow all that's happening is a disservice to an entire half of the population.
They're denying science for ideological ends. It's pretty much the same thing as conservatives with climate change. They don't like what science has to say, so they're trying to shut it down.
I'm generally pro-feminism, but no 'side' has a monopoly on bad opinions.
'Blank slate theory' simply isn't what feminists are arguing; they are arguing that our society has a woefully poor record of hastily ascribing traits to a kind of biological determinism, and further claims of that type should be heavily scrutinised.