I don't think this screen would prevent anyone doing CSA from sending that M, and a C independently wishing to send SM is not necessarily being A, so I'm not sure what you mean
Does that sort of content show up often for people who would not prefer it and don't go looking for it?
As someone who's used earlier versions of iOS for some years now, and who knows a bunch more people who also have, that's not a problem I'm aware any of us ever experiencing. I realise that anecdotes are not data, but it doesn't seem like it should be a common issue at all...
That's not what your article is about though, or even so much as mentions in passing, so I find the critique that the provided data is not about CSAM legitimate