This quote by Prof. Begoz cannot be right, considering the quote you gave from John ch 6 and what you said about the communion prayers. It sounds from post 14 like Scriptural context has determined the language we use.
The body is considered anthropologically neutral in the ascetic literature, where the context is that the Fathers are trying to say that sin does not originate in the body, but only in the soul, although the body participates in the sin or the righteousness of the soul.
I would suggest that for the use of these words, context is everything.
A remarkable aspect of Byzantine anthropology ...