The rehabilitation counselors act like know-it-alls (superior, bossy, they know more than everyone else). When they do this it creates an exclusive in-group for them and makes them feel and seem indispensable. In the sentence, 'they' were surmising that the counselors were controlling their clients this way so that others would continue to believe that they and the job they were doing were necessary. So they were acting this way, not to help their clients, to do good, or to be useful in any way. It was merely to protect their jobs.