It looks like it has to do more with neck armor elements than shoulderpads, I've had it happen on the Blade Savant armor that has no fancy shoulderness.
Now try that hair bug while riding a speeder... gives a new meaning to hair blowing in the breeze -- it looks more like an alien creature clinging on for dear life.
The bug might be tied to how this hair is less static than others, it does have some bounce and falls straight down when your head looks down (i.e. a smuggler or operative ducking behind cover) -- which would make sense seeing how horribly it glitches on some armors while on a speeder.
Need to test it with that headbanging emote...