##Narrative Necessity
Narrative Necessity
As Zack Handlen pointed out ten years ago in this article, in order for the whole episode to even work, Pike has to be essentially caged within his own mind and body, utterly unable to move, unable to communicate, unable to connect.
If he were able to flash Morse Code, he'd be one step below Sir Stephen Hawking, similarly wheelchair bound but able to speak using a computer interface voice.
Narrative Necessity is any particular person, object, state, or event that must exist or occur in order for the plot to function. Without it, the story falls apart. In this case, in order for Spock to pull off stealing the Enterprise, kidnapping Pike and wasting time with the whole court martial thing, Pike needs to be as absolutely crippled as he can be without actually being in a coma. In order for Pike to be perfectly aware and conscious but simultaneously non-communicative, he must be deprived of all means of communication.
In this state, the story can function. Because, of course, the real answer is of course they còuldcould have used Morse Code! They could have hired a Vulcan nurse's aid to be in constant mind-meld with him. They could have rigged up some kind of speech synthesis computer interface (20th century tech!). Any of those alternatives would have destroyed the narrative necessity and thus precluded the Menagerie episode's plot from ever happening.