she has no incentive to release funds to bob Then in case case, bob having an issue with the transaction (alice refuses to pay) can issue a escrow_dispute_operation leaving the matter to amazon to solve (eg: pay bob).

And he has to fit within escrow_expiration, because if he does not, alice could snatch back the payment before he does No if there's a dispute, expiration no longer counts and the agent has infinite time to figure it out. If both parties can't come to an agreement, the funds will stay locked forever.