It does sound like a very tragic situation but I think there could well be justifiable reasons for a forced caesarian in very rare circumstances, yes. I have no knowledge of this particular case but I have worked with people so acutely mentally unwell that they don't believe they are pregnant, believe that the baby inside them is a demon who must be killed/expunged and have tried to get the baby out themselves via methods that could have killed both themselves and their almost full term baby etc. It is very common for people who are psychotic to not believe that they need treatment for physical illnesses and I could imagine a scenario where someone acutely mentally unwell refused to accept that they had pre-ecampsia and needed to deliver their baby early, for example. Bipolar affective disorder is an illness that can cause acute manic psychosis at one pole and extreme depression at the other. Both mania and depression when they are severe can be life threatening and certainly can severely affect someone's ability to make decisions of all kinds. I think it can be difficult to imagine how ill someone with a very serious mental illness can be when they are acutely unwell unless you have experienced it via work or a very ill family member. Even though mental illness is very common, most mental illnesses are spectrum disorders, if you like, and there can be chronic or acute phases, as well as periods of remission and sometimes full recovery. The same person when well can seem utterly unrecognisable from when they were acutely unwell and severe bipolar disorder is perhaps one of the mental illnesses where this contrast is most stark.
This would have been authorised by a judge at the court of protection on the grounds that the mother lacked capacity to make a decision about whether or not to have a caesarian at the time and, if that lack of capacity was accepted, that it was in her best interests to have one. Evidence of the extent of her mental illness would have been presented by adult mental health services and the obstetric reasons for the necessity of the c-section by obstetric experts, I imagine. It is a decision that would not have been taken lightly, of that I am sure.
Hideous situation, difficult decision, no right answers maybe. But would it have been better to risk this woman's life rather than force a c-section? I suspect that we are talking about a life threatening situation here because Court of Protection cases of this nature generally are about making life and death decisions on behalf of someone lacking capacity.