I think it's a combination of career-protection as I said earlier, and also a deep simplification of complex thinking. If everyone around you is shouting 'TERFs are evil! They are committing violence against trans people and want them dead! Even asking to "debate" trans rights means you're coming from an anti-trans stance!" (as someone said in the linked Times article) then I think it's really tricky to let other voices in.
I know I bought into it all in the early days, wanting to be OTRSOH and hearing the echoes of early Stonewall battles, watching the far-right and populism grow across the western world - this seemed a clear and easy way to back vulnerable people and battle against fascist forces that only cared about white, straight men.
It was a drip-drip of articles, podcasts, and of course MN threads that slowly woke me up to the practical realities of all of these "new truths", and they only crept into my life because I'd pulled back from my arts career. When these people are in the absolute thick of it, surrounded by voices getting huge (but still niche) public acclaim for sharing misinformation because it fits with a great narrative of vulnerability and heroism, it would be almost impossible for them to say (like most people on MN do), 'Trans people deserve safety and security and currently have huge protections under the law to ensure these, so can we talk about what women and girls might lose in terms of their own safety and security when TWAW?'
I can't imagine any of those people having the guts to do that in a million years. I am also 99% sure that at least a handful of names who I know quite vaguely on that list are highly, highly GC.