There is even more to it. The situation at Dunbar Towers and at other occations prove that TOWTM has to utter commandos in order to organize his army. Moreover, the zombies seem to have perserved some of their intelligence. The simple sentence "Leave her alone" requires the ability to reason. Even the brain-deadest (?) zombie has to recognize CJ as a living being or even a person. The whole thing would have been pointless, otherwise.

But it is just one of the various mysteries. Does TOWTM eat? Why does he not bite humans? And so on, ...