OP is incorrect both on AA's safety & security policy (which then becomes FAA rule once filed and accepted by FAA) and the underlying impact.
The safety & security policy is that small devices go into airplane mode from the "cabin door closed to 10,000" on departure unless the Captain permits or requires otherwise.
Needless to say, trying to get passengers to pay attention has nothing to do with this as passengers may still watch off-line video.
The failure to follow a crewmember instruction may constitute a criminal offense or result in a civil penalty of up to $11,000.