I'm torn on this one. One one side, it was an unprofessional thing for the controller to do. However, I don't think safety was compromised, since the situation was not much different than having an ATC student being supervised (yes, the child doesn't have the technical knowledge necessary, but he is not taking any decisions, just repeating what he was told to say).
Just give the controller a warning or something of the sort and let him keep his job.