ommis, it is not just semantics that you are arguing. complete emunah is believing that whatever happens, happened by the hand of Hashem. Levi Aron was the shaliach. He could have chosen to not be the shaliach, but this terrible tragedy would have happened nonetheless.
A separate questions is why Hashem did this, and what we are supposed to learn from it. Whatever that is, we better learn it well, and quickly!