An Allianz OneTrip Premiere trip insurance covers $2000 for loss or theft of baggage and personal effects. They reported the loss to airport security. Getting a written notice of that report ought to be enough to file a claim.
I thought that you meant the insurance company would reimburse for a mac that was returned to you without physical damage but locked by Apple.
Also, how can you even assess that the laptop has no physical damage? They can't boot into the OS and can't see that the laptop is in fact completely physically intact. What if the other party broke the webcam or one of the USB ports?
I really, really doubt a travel insurance company would pay out on this one.
If someone grabs your laptop and takes it in an airplane that takes off without you, it's arguably been lost or in fact been stolen.