If they have Malora cooperating I'd be unlikely to try anything against him like this. We'd be scouting first to find things like that out.
I would put a safeguard on things to make sure we're keeping an eye on Jorah. Ideally we just have Ithroen hitch a ride in his skull, but not take control, to ensure we know if he would betray us or not. If he does, Ithroen just takes control and brings him to us and we plan out what to do from there. Get our Possession up to Level 3 if Ithroen isn't back, and have a bird deliver the note - the note will tell him to follow the bird, alone, to another location we specify. It'll reveal we're a warg, but that might just scare him into submitting more. That's where we'd give him our demands. He'd have no clue where our base is, and we could keep watch on him via Possession of another bird to see if he tries to screw us over. We could also make our orders to him involve him going and giving his First Men some orders, and then coming back immediately so we can keep an eye on him to make sure he doesn't screw us between then and the scheduled attack.