Of course he was writing a parody of Macbeth. The stepfather, the mother. It’s transparent. The vulgarity of the piece and crudeness is a little tough to stomach, frankly.
Had this been an isolated submission, I don’t think it would have led to his being sent for psych evaluation. I reckon his writing and demeanor was creeping out the entire class for some time. That seems to be borne out by the earlier post quoting a former classmate in the writing class.