Labour are avowed centrists now, and centrism is a form of extremism that denies morality in politics. There is no right thing or wrong thing to do, there are only middle things to do.
They've let the far right decide where the middle thing is on trans rights by letting exterminationism be one of the sides to find a middle ground with, instead of rejecting the idea of debating human rights *outright*, which a progressive party would do.