Great article and thanks for the link! This is one of the things that has made me so very angry over the last couple of years - Susie Green was totally open about who she was, what she did, why she did it, and she and everyone around her managed to spin it as brave defiance of social norms for her child's sake. And so many people who should have known better just nodded along.
But the story I've occasionally seen putting all the blame on her and saying that Mermaids was just a harmless support organisation until she came along doesn't ring true to me, because that's not how I remember Mermaids from the 1990s. Admittedly they were so fringe I didn't pay them a lot of attention but they weren't an organisation we'd list in my feminist and women's group's resources. They may have had a wider range of voice at the time but she wasn't alone, she was only the most extreme.
So I don't need to know why Mermaids ditched her. There are so many good reasons, take your pick. And as for why they kept her so long, well given how much respectability success and influence Mermaids managed to wield under her leadership and how afraid everyone else was to call out abuse, why wouldn't they keep her as long as possible?