What is the name for the psychological therapy involving socially isolating a patient?
In my recent graduate school psychology training, no therapy of this type was ever mentioned. In fact, conversion disorders are under some scrutiny because, in at least 33% of cases, an organic cause eventually is discerned. Medscape on conversion disorders 
In-patient treatment is uncommon these days, and most modern psychological treatment includes increasing social support, activating the patient with exercise and meaningful activity. 
I would be concerned about the nutritional and, more seriously, the emotional impact of this unusual form of "treatment". 
BTW, Extinction, as a therapy, usually refers to a phobia treatment with relaxation training and progressive exposure to the feared stimulus.