I found the stories in this book by psychiatrist Ira Steinman helpful - "Treating the Untreatable" - several cases similarly difficult to how your mom sounds. Sorry to hear about her difficulty.
https://www.amazon.com/Treating-Untreatable-Healing-Realms-Madness/dp/1855756099/
I think if you read the interview carefully, you'd see that Buhner does acknowledge the reality of very severe distress, and that he has worked successfully with some very disturbed people.
As an example of other successful ways of approaching these problems, let me invite you to check out several stories from people who either were paranoid or catatonic "schizophrenics" - and fully recovered - or who were therapists working with such people to help them heal:
Caleb’s story: https://www.madinamerica.com/2016/11/best-kept-secret/
Lois’ story: https://www.madinamerica.com/2016/11/curing-schizophrenia-via-intensive-psychotherapy/
Daniel’s story: https://www.madinamerica.com/2012/08/a-new-understanding-of-psychosis/
Eleanor’s story: https://www.ted.com/talks/eleanor_longden_the_voices_in_my_head
“Rethinking Madness”; Six case studies here: http://www.rethinkingmadness.com/download/i/mark_dl/u/4007924736/4629448798/Rethinking_Madness_complete.pdf
“Treating the Untreatable – Healing in the Realms of Madness”; 13 case studies: https://www.amazon.com/Treating-Untreatable-Healing-Realms-Madness/dp/1855756099
“Weathering the Storms – Psychotherapy for Psychosis”; 12 case studies: https://www.amazon.com/Weathering-Storms-Psychotherapy-Murray-Jackson/dp/1855752670
As a person who was once on the type of ward you describe, and was myself once nonfunctional and paranoid, let me say that these stories show that alternative psychodynamic approaches can work well with schizophrenia, and sometimes be profoundly successful in helping psychotic people recover. In his book "Plants and the Imaginal Realm", Buhner wrote with great insight about having done this type of depth work with paranoid and/or catatonic people.