It seems that it's impossible to destroy the Motus in Athnias. I fell off a cliff an noticed that it didn't even touch the ground, so I tried it a few more times from different cliffs and every time it just bounced off the ground without touching it because of its hovering ability. Afterwards, I tried shooting it, but it still took no damage whatsoever. It might not even be a bug, but I thought I should let you know.