Docetism may be the denial of the reality of Jesus' humanity. And I do not think Pelayo has strayed to that point. Perhaps, a truncation of Jesus' humanity is a better way of characterizing the view which seems to be expressed. If Jesus could not sin, then what was acted out on earth was a divine farce. Now, one could say that there is no possibility that Jesus would sin and that would make all the difference. But to say that He could not sin removes him from the realm of humanity (even the initial form of humanity expressed by Adam and Eve, before the fall).
Pelayo's view seems to fit under the category of Apollinarianism (the friend of Athanasius, Apollinarius) which emphasized the deity of Jesus to the effective suppression of his humanity. It was condemned at the Council of Constantinople in 381.
I don't think Pelayo was empasizing Jesus's diety to that extent. I certainly see much more effort here to suppress Jesus' divinity. Do you not admit with me that there is an essential paradox inherent in the Incarnation? That, as I said, Jesus had to be able to freely choose to sin, and yet could not possibly have ended up doing so?
SD