It's clutching at straws to say that female sex offenders exist and claim that policy should be centred around that. Of course they exist, but they are few and far between, and the only ones I can think of (although I'm no expert on the subject) have committed crimes against children, rather than men, and in any case they wouldn't be in a male prison. A woman who has sexually abused children would be segregated for her own safety in a woman's prison.
Isn't it a widely held view that sex crimes are about power, rather than sex, so in most cases they are carried out by the strong on the weak? It doesn't surprise me, therefore, that the numbers of transwomen sex offenders will be greater than the number of women imprisoned for sex offences. Not only that, the number of male violent criminals is far greater than the number of female ones, and the number of assaults by men on women is far greater than the other way round.
For all of those reasons, plus the fact that the majority of transwomen are not medically transitioned, so have penises and male hormones, it makes no sense at all to house them in female prisons.
It may well be the case that transwomen are at risk in male prisons, but I can see no reason why the answer to that should be to house them in female ones, particularly if they have been convicted of sex crimes or crimes of violence. What sort of logic, other than one based on misogyny, would see that as a good idea?