Brrrt--
I was taught to use "-body" when the pronoun is in the objective case (direct, or indirect object).

"That" is used with inanimate objects / concepts / non-persons and "who" is used with persons. Obviously, it would sound strange to hear "Move that chair, who is in the way."

Equally obviously, your attention to English grammar is better than the vast majority of native speakers in the United States, and dare I suggest, in many of the Commonwealth countries, as well.