 Why does Hendricks help Joe?
There were no longer any prisons—CPA officials had declared loudly and emphatically that their job was to prevent crime, not punish it. Instead, he was sent to a hospital where all criminal tendencies were removed from his mind by psychologists, shock treatments, encephalographic devices, a form of prefrontal lobotomy and a dozen other methods. The President of the United States was a capable man, but also a very handsome one, and the fact that a man who looked something like a bulldog had been elected as New York's police commissioner was a credit to Hendricks and millions of women voters. Hendricks rose from behind the desk, walked leisurely to where Joe was slouched in a chair.
 Hendricks knows Joe will not go for the free treatment.
 Hendricks knows becoming an EX is the way for Joe to get an excellent job.  Hendricks helps Joe because they are friends.  Hendricks knows Joe will not go for the free treatment.  Hendricks thinks he can also become an EX and get an excellent job if he helps Joe.