That is not correct. The airplane experiences this uniformly because the wings transmit the forces to the fuselage. But the contents of the aircraft follow Sir Issac Newton and want to continue their previous motion. If the aircraft experiences high enough negative G then anything not strapped down will appear to rise relative to the fuselage.
To put it another way: you need a physical connection (eg seatbelt or cargo strap) to transmit the force in such an event, just as the fuselage needs a connection to the wings to transmit the force.
