I can't think of a single 90 degree swivel headphone that doesn't face the drivers up instead of down when you drop them to your neck. It's why I wear all of mine backwards when portable.
The only time I see a swivel headphone's back plates when they swivel is when placing them on a desk, then their driver is facing down. When wearing them and you do that, the driver faces up.
I don't see why they don't all have 180 degree swivel. It can't be an engineering problem.