If you can reduce the risk of 50% of the prison population by 95% by such a straightforward measure as separating them from the other 50% it would be negligent not to.
D'oh, obvious error here. Women aren't 50% of the prison population. That's cos I was busy editing this, and started from a more general point about safeguarding 50% of the population.
In prison, of course, women are an actual minority, and hence even more vulnerable. Can you imagine a fully-mixed prison scenario with 95% male and 5% female? No, that 5% needs to be segregated.
50% of the potential prison population, I guess, even though a woman is less likely to end up there.