I appealed to common usage and the fact that we say Christ’s body was placed in the tomb against McCusker’s attempted restriction of the word body to living bodies. I shall also appeal to St. Thomas against George and Lee’s attempted restriction of the word part to a usage in which, if I understand correctly, a human being’s material remains are not part of him. “Understood in this way,” St. Thomas says, “body will be an integral and material part of the animal, because in this way the soul will be beyond what is signified by the term body, and it will supervene on the body such that from these two, namely the soul and the body, the animal is constituted as from parts” (De Ente et Essentia, cap. ii (my translation of which is here).
There is a perfectly good sense in which, even dead, the body is a part—the material part—of the person. Indeed, it’s the part you get when you subtract the soul, which George and Lee, I think, admit is a part of the person. Since a whole less a proper part leaves a part, even the dead body must be a part of the person in some sense.
But McCusker, I take it, is not restricting 'body' to living bodies, but is pointing out that when we apply the term to living and dead bodies, we are using the term equivocally; and that of these two usages, the application to the living body is the more fundamental. And Aquinas clearly falls on the side of McCusker, George, and Lee. He is, after all, Aristotelian, and is always very clear that a corpse is not a body, and especially not a human body, in the same sense that a living human body is. The passage from De Ente et Essentia that Miller is quoting is clearly about the body as animated by its form.
An interesting context in which Aquinas discusses this point is the relics of saints. Aquinas considers the objection that, since a dead body is not of the same species as a living body, we should not respect the bodies of saints. This has some force, and Aquinas concedes the premise, simply denying that the conclusion follows:
The dead body of a saint is not identical with that which the saint had during life, on account of the difference of form, viz. the soul: but it is the same by identity of matter, which is destined to be reunited to its form.
This suggests a way in which Miller could build a Thomistic position, despite his divergence from Thomas on such a key point as whether a dead body is part of a person (rather than merely a former part of a person, considered materially). As Augustine notes in a passage Aquinas quotes, if we respect even the possessions of the dead because of their connection to the one who once was alive, even more so should we respect the body of the dead. And this is so even if, as Thomists hold, it is not 'the body of John' in the same sense it was when John was alive.
On the issue of Christ in the tomb, the standard scholastic argument is that he is a special case. Christ was in the tomb, recall, after His institution of the Eucharist; and so the standard view is that Christ's body is always united to the Word, because of the Word's divine power, even when it is not united to the soul. Aquinas alludes to this position as his own when talking about Christ's descent into hell.