Starmer also has to pander to racists, he also has to pander to anti-EU hardliners. That's the reality of politics - Labour is a broad coalition of working class voters, metropolitan liberals, Trots and everyone in between. I might not like the fact that Labour has to tread a middle ground, but the reality is that if they don't then we get the Tories.
That won't be good for Trans-people at all.
The way you protect marginalised groups is by empowering a left-wing coalition and changing the law. Starmer knows this, you seem smart so you must know this too. Many Trans-people are angry at him for not condemning everyone they disagree with but the reality is that this would empower every single marginalised group to demand their position takes priority and collapse any chance of a left-wing government. The vast majority of people in the UK do not care one iota if someone is Trans or not, I certainly don't, but it's worth noting that being Trans does not prevent someone from being either a) an idiot, b) unreasonable or c) an unreasonable idiot. In echo chambers, the loudest and most vociferous voices rise to the top.... it's not ideal. Sometimes those within the community aren't the best advocates for their community. https://medium.com/p/86d6cb79aa11
If Labour want to avoid an identity based shit show then they need to tread carefully. You might think that makes him a gigantic piece of shit, I think that makes him a pragmatist.