I think it is ridiculous that they will only let passengers with an AY ticket use the priority security. It should be available to oneworld status holders on any oneworld flight + business class passengers just like it is with oneworld lounge access.
I have however had luck sneaking in to the priority line twice with an AB ticket (op. by AY) just by showing my AY Plat card and flashing the boarding pass to the agent so that my thump hides the flight number. So far it has worked well but it is for sure not guaranteed to work every time until they revoke this stupid AY ticket only rule.