Everything is pointing out that there must be an express will for the Baptism to be valid.
Pope Innocent III in Ex Parte Tua, 1206 writes:
The sleeping and the weak-minded, if before they incurred weakmindedness or before they went to sleep persisted in contradiction.......They do not receive the sign of the Sacrament.
Fundamentals of Catholic Dogma:
In the case of adults, an habitual desire at least to receive Baptism is requisite for the valid reception of Baptism. The worthy reception of the Sacrament demands an inner disposition, which must comprehend at least faith and sorrow for sins committed.
It makes sense that God will not save one who has spent their lives rejecting Him simply because you "baptize" them while they are in a state where they cannot make that decision. However, I think you can at least try. You don't lose anything by trying to baptize an unconscious dying Non- Catholic person. What would be the worst that can happen? At worst they get wet and at best they are baptized and therefore can enter Heaven.