I'd expect they act like other followers and npcs ignore then when sneaking & undetected. But I would not be surprised if out of sneak they beeline to nearest foe and aggro em. Cadwell does that. And I just did the Mages guild on alt and Valaste did that all thru in Eyavea - while complaining about me harming the nice cute Daedra. (No remorse for choosing the extra skillpoints after that.)