Well, auto only means “him” in oblique cases, but nonetheless, I don’t see how this establishes your point. The saints of the most high are portrayed as a single man in the vision.
What’s more, also in the Greek, “Most High” does not appear as its own word. Agois upsisto means “the highest holy ones.” The definite article is a translational interpolation.
If your point is correct, then anytime God or a characteristic of God shows up as part of a word, then the most likely referent for that word is God Himself, which would have startling implications for, say, Elijah.