Can a man have a vulva? A trans man obviously can.
Can a non-binary person have a vulva? A penis? They clearly can have either, because non-binary is a pure identity having nothing to do with biological sex.
The problem is that two different definitions of 'women and girls' and 'men and boys' are mashed together all the time when activists write about these issues.
Either 'women and girls' refers to biological sex or it does not. When it does refer to biological sex adding 'women and girls' and 'men and boys' to a list which ALSO includes non-binary immediately turns it back into a term describing an identity only.
It's that non-binary label which collapses the edifice Phillips is trying to build here. If I write about the reproductive rights of women, some non-binary female-bodied person will immediately complain about their needs being forgotten, and if I answer that I use the term in its biological definition they protest that they are not 'women' because they don't identify as such.
So it is a battle to try to hold on to the meanings of the words, not just a battle to distinguish natal women from trans women in contexts where that matters.
And this is what is happening now.