Welcome to the post-factual world, where anything can mean anything!
There is a clear, verifiable, scientific definition of woman/female and man/woman. The fact that it is verifiable and consistent makes it more true than any alternative definitions. The alternative definitions lack clarity and consistency - current usage of 'woman' to also mean 'some men' by a small number of people is not the same as an established definition.
The established meaning of 'woman/female and man/male works fine for the majority of people, in the majority of contexts.
That it does not suit a very small number of people is challenging for them, but the solution is not to skew the established meaning of words and claim that other 'competing definitions' are just as true.
That is clearly unreasonable and disproportionate and I believe that makes it unfair and unacceptable.