Dr. Wolff, There seems to be an assumption that a worker produces a surplus. However, there are commonly employees, by no means owners or management, in a firm that objectively only produce more work for others, effectively diminishing total production, yet keep their jobs in perpetuity. Given most of the world is already in capitalism overdrive, how can this be?
Economic theories usually aim at typical, "normal" arrangements in the production and distribution of goods and services as their objects. If they are honest and self-aware (unfortunately a small minority of them these days), they know that all sorts of atypical and abnormal arrangements exist and last. There are, to take your example, all sorts of circumstances in which a person is kept employed who adds little or nothing to output and even decreases it by his/her interferences in others' efforts, etc. The pressures of family, kinship, romantic, religious, and other relationships within workplaces produce that sort of outcome all the time. In some ways, capitalism as a system reduces such atypical relationships, but simultaneously, in other ways, capitalism fosters them. A better economics would acknowledge all this and take those other circumstances into account and into the cores of the theories.