Ellison's pseudonym was Cordwainer Bird, which was partly in honor of Cordwainer Smith, the pseudonym author Paul M. A. Linebarger used on his science fiction. He used the Bird pseudonym as sort of his personal Alan Smithee, when he wanted to take his name off of something in protest. So it's odd that he left his real name on "City" when he's been protesting about it ever since.
Roddenberry apparently talked Ellison into using his real name on the episode (he managed the same thing with D.C. Fontana on "The Enterprise Incident"). Amusingly, an earlier draft of the episode was (jokingly) credited to Cordwainer Bird. That, obviously, was before Ellison's relationship with Roddenberry and Star Trek