If we take OJ's rebuttal piece seriously (and he hasn't always been a good faith debater), I wonder if part of the problem is that women / feminism doesn't really fit into what he classes as his socialist world view of automatically backing what he sees as the oppressed party no matter what - as there are fewer trans people than there are women OJ will always back the former.
(On a similar note there was a featured comment on the Guido Fawkes site where someone explained how it was hard for those with a Marxist approach to deal with the ISIS as Marxism has no religious aspect. I took this to mean that, rather than consider them religious fundamentalists looking to inflict their beliefs on the rest of the world, those whose worldview is always through this rigid prism could still see them as the oppressed minority as a racial or cultural group. Obviously this is on a different level to the current trans debate but I do think the connection is the limitations of always considering issues via a simple oppressor/ oppressed approach - I know it's possible to argue that women are the oppressed party in the trans issue but my personal view would be that it's better to abandon that game rather than try to win it and focus rather on the safeguarding angle - the practical angle will do better with the general public than a theoretical one).