I get where you are coming from, but it looks to me that the TAs in Labour are in a difficult spot and are weak in the party. As you say the Starmer regime has been inconsistent in a bunch of areas marked by a bunch of u-turns. Opposition inside the party has forced a bunch of changes on other matters yet on sex/gender the victories from the TA side are like the fox botherer's victories actually non-existent in recent times.
An early big loss was Labour in May 2025 explicitly confirming that the Supreme Court judgement was completely accepted inside the party and where the Labour rulebook said women they meant actual women. Read it here:
https://labour.org.uk/resources/supreme-court-judgment-faqs/
There has been no indication of major pushback against this inside the party under Starmer. Local parties can pass motions to argue for changes, they can bring this up in conference. They can't argue the party should break the law though. Not much sign of real fightback. The best the TAs got was not having a women's conference at all in 2025. The women's conference in 2026 is going ahead in September and there will be a special side event for men in dresses OUTSIDE the conference itself. This is Labour being "nice":
https://labourlist.org/2025/12/exclusive-labour-nec-womens-conference-and-local-elections/
This is indeed real positive action from Labour and when TAs are in control it is women proclaiming women are a thing who are outside the conference. Still going on with the Greens.
The guidance itself after a huge wait turns out to be virtually the same as the original guidance just with a lot of extra worded examples. It clearly embodies the idea that biological sex is a thing like the law does. Yes it could be better, but the reaction of the TAs shows they see it as a disaster.
The EDM motion against the guidance has 148 signatures - 80 from Labour MPs out of 403 Labour MPs. Yes Labour MPs inside government, a total of 93, can't sign ED motions, but if there were a lot of TAs on the front benches then why are they not changing policy from the inside? Out of 310 Labour MPs who can sign the total of 80 is 25.8% of the MPs. Bearing in mind signing an EDM doesn't actually mean much, if the parliamentary party was that anti women we would see more of it. If they are going to do something REAL to oppose the guidance the clock is ticking the 40 days expires on July 9th.
As I said though the next crunch point is the conversion therapy bill which Labour are bringing forward very soon it seems I think it will drop in July or August. We DON'T know yet what it will look like. However it will have to either conform to existing law about the existence of biological sex or aim to change it openly. The only thing we can say for sure is if Labour were planning to change the definition of sex they would have obviously delayed the guidance till after the bill.
I think the conversion therapy bill may actually possibly codify the TAs worst nightmare. It may have a section which says biological sex is a thing and that therapists should not pretend it is not. It may actually protect gay people from being pushed into transition and protect professionals who want to help them.
This is of course speculation on my part, but given Labour accept the Cass review which warned about that issue it is certainly possible. Also we have to bear in mind Labour is sort of scared of losing Muslim support so I think the conversion therapy bill will be very carefully worded with that in mind that indicates a standard definition of sex. Note unlike the TAs the Gaza faction has forced a bunch of changes from Labour. Not as much as they would like, but they had real pushback.
On the other hand the bill may attempt to bring in more gender crazy by the back door. I totally admit that.
We will find out very soon. The only certain thing is we are going to be debating all of it in public and if we don't like it we can push back... HARD. If we do that we can win. The SNP have seen that. So has Burnham.