If you think about it, Ar could be either of the Mafia roles.
Mafia, kill Medzh and Kosh, because they're interfering with Town and Nebo's investigation.
Yesterday, I was arguing with Ment. He said, "I believe Medzh, I'll vote like him, but please let Nebo confirm his role." (WHAT!?)
And even so, killing Morny is quite explainable by the fact that there might have been more peaceful people who could be protected/healed, and no one even suspected him of being Mafia and everyone thought he was Town, so he was a perfectly logical target.