In terms of treatment whether one has a diagnosis of schizophrenia or schizoaffective disorder, I think, does not matter much. In terms of treatment in either case the cornerstone of treatment would be antipsychotics. With either diagnosis one could get MDs to prescribe anti-depressants. I do not think psychotherapy is appropriate when there is a psychosis as one is already too much inside one’s head. With a diagnosis of schizoaffective disorder there would be the temptation to try psychotherapy.
Psychiatric diagnoses are not grounded in biology. The diagnosis being off a bit does not matter greatly. Some individuals will be more comfortable with one diagnosis rather than another. Outside research there is no right or wrong choice between schizophrenia or schizoaffective. Practically given a diagnosis of bipolar disorder is at all sensible then one would go for the diagnosis of bipolar disorder as the stigma attached to bipolar disorder is an order of magnitude less than the stigma attached to schizophrenia of any sort.