The link has opened for me now, and I've had a look. Pink News is an LGBT(Q+) paper, and as such is very pro-trans in its outlook, so I'm not really surprised at the article.
The trouble is, that men who have transitioned, or those who are genuinely 'living as' women are likely to be at risk in women's jails, and there is a huge difference between them and male sex offenders who are willing to say they are women to get access to victims, and to spare themselves the hard time that sex offenders would get in a male prison.
Trying to get a fair deal for everyone is very tricky. The idea that there should be separate 'trans' wings is highly unlikely to get off the ground at a time when funding to jails is being cut, and anyway, housing 'genuine' (sorry, but I can't think of a better word) transwomen alongside male-bodied rapists and other violent offenders is bound to be dangerous for them.
What I would say is that this should be a male problem, not one that female prisoners should be expected to take on. It is men who become transwomen, and male prisons are meant to house men. Why should women, yet again, be expected to bear the brunt of what is, essentially, a male issue. Nobody wants to be locked up next to a violent sex offender, but IMO the majority of male prisoners would be better able to cope with this than the majority of female ones.
Which still leaves the question of the 'genuine' transwomen who are going to be vulnerable wherever they are, I suspect.
The thing is, if not for the ability to self-identify, we would have statistics on how many transwomen offend at all, but as it is, there can't be any stats, so there is no way of knowing if there are any 'genuine' TW in jail (in which case there would be less of a need for a policy to protect them), or if the numbers are very high.