The way it would work would be that an arbitrator would create a bot to take the offers and then use the key from the taker bot and their arbitrator key to steal the escrow which contains the seller's Monero plus their security deposit. It seems like the two ways to avoid this would be to either A: have a bunch of arbitrators so that any one arbitrator is not chosen for the vast majority of the offers or B: make offer taking a request process instead of a demand process.