I've read that argument and, with all due respect, it is a bit flimsy. First, to compare God with King David or David's nature is a bit of a stretch. God's way are not man's ways. This view imputes a man's value onto God.
Our Lord Jesus made no differentiation between His mother and any other believer in the crowd.
as Inigo Montoya said: "You keep using that word. I do not think it means what you think it means."
English and latin don't mix that well. "co-" does not mean equal to in any way at all. I'm sure you've been told that many times.