The individual needs and feelings and wishes and rights of the person born male always is the first consideration over the entire class of people born female.
The inequality of consideration, regard, value, is screamingly obvious.
And there are other solutions to managing the needs of transwomen prisoners than simply utilising the female estate as is. Let's be honest about this. This is not about safety or proper care of or dignity because all of that could be provided to a high quality in third space or trans specific prison wings. This is purely and simply about affirming identity by placing transwomen with female people as female people themselves.
However the amount of consideration given to one of those parties and the total lack of consideration at all given to the other makes it very clear that no one involved in the decision believes that there is no difference between the two groups. They know exactly whose consent and interests and feelings matter and whose consent, involvement in decisions, choice, safety and right not to be harassed, assaulted or raped doesn't. They are very clear on the sex based thinking in all this.
As mentioned above: if the safety of TM cannot be considered possible in the male estate then there is the admittance that sex exists and in some situations it must be regarded for the safety and needs of all. However that thinking is not then extended to female people, and the female estate.
No one should be incarcerated in situations where their privacy, dignity, safety, freedom from harassment and freedom from assault and physical danger cannot be assured. No transwoman. And no women either. It is pointless trying to force a reality to exist that these two groups can be combined in all situations when it is only the benefit of one group and to the detriment of the other: when solutions could perfectly well be found by parallel separate provisions.
Lets be honest about what the barrier here is. And why this practical, realistic, perfectly possible starting tomorrow solution that would meet all needs equally and safely is not acceptable.