A central issue in the trial was whether D.J. is profoundly cognitively impaired, as the prosecution contended and the court seemed to accept, or is competent cognitively but unable to communicate his thoughts without highly skilled assistance, as the defense contended. If we assume that he is profoundly cognitively impaired, we should concede that he cannot understand the normal significance of sexual relations between persons or the meaning and significance of sexual violation. These are, after all, difficult to articulate even for persons of normal cognitive capacity. In that case, he is incapable of giving or withholding informed consent to sexual relations; indeed, he may lack the concept of consent altogether.
Secular progressives (as well as "progressive Christians") generally treat consent as the sine qua non to distinguish licit sex from illicit sex. They resent it when Christians compare homosexuality to other sexual deviations that lack consent.
But notice how the argument of secular ethicist Peter Singer and his coauthor nullifies the consent criterion in reference to the developmentally disabled. Moreover, the logic of their position would abolish the age of consent on the grounds that young children lack the concept of consent, and so they can't withhold consent. Their position logically turns the rationale for age of consent laws on their head. Inability to consent becomes a justification for nonconsensual sex rather than a bar.