My friend on board says the bang occurred as he nose was lifted, followed by a huge amount of vibration. I honestly don't know if his recollection is correct
It's possible that your friend heard the bang, then felt the deceleration as a nose down pitch, thereby thinking that they had already pitched up. (this is the same way simulators work).
And you are correct - if the nose was off the ground, there's no reason they'd be stopping...