I think all of this is addressed for the next update. Charm has been reworked to act more like it would be expected to.

* When a mob is charmed, it should attack other mobs, and ignore players.
* Charmed mobs cannot damage players.
* Charmed mobs consider other mobs enemies and vice-versa.
* Players can target and damage charmed mobs, and they won't fight back until uncharmed.