I define woman as adult human female but as I'm nothing to do with the implementation of this law that is completely irrelevant.
It is relevant if you want to protect adult human females. Because unfortunately we are likely to end up with a "misogyny" law that protects transwomen from any adult human females who argue that transwomen are not women and need to be distinguished from women for the sake of women's safety, privacy, dignity and autonomy.
That failure to protect women may not be most people's intention but it is some people's intention, and if that's the effect then intended or not it's bad news for women (the adult human female sort)
I don't think anyone is above the law, even gender critical women.
If no-one is above the law then we need to be extra careful not to create bad laws by accident.
As do the Fawcett Commission, as linked.
The Fawcett Society don't define woman as "adult human female" and they don't seem to mind what happens to women when society fails to make that distinction. So they're contentious, not authoritative.