I would hope that if they were to implement turbulence stabilization in VR they won’t lock to horizon. Instead, they should have the camera’s pitch, tilt, and roll follow the plane’s orientation with some sort of smoothing filter applied. The smoothing filter shouldn’t be too aggressive and smooth out the movement too much or you will get a sickening effect where it feels like your view is lagging behind the plane. It should be tuned to where it will soften most of the turbulence, but not be so smooth that the camera will stay caught up with large movements.
Lock to horizon works in racing sims because your vehicle will be aligned to the horizon in most circumstances. Banked turns and steep hills break that immersion, however. It will not work in a flight sim because a plane can freely tilt and pitch.
Therefore, smoothing the rotation of the camera would be a better solution in my opinion.
I have actually implemented a similar type of VR camera for BeamNG famously known as the Enhanced Interior Camera. It has a “VR Thrill” preset that uses a hybrid approach using a mixture of rotation smoothing and lock to horizon. It seems to work pretty good with plane mods, too! Though, it’s not designed for them as it reverts to attaching to the vehicle while upside-down and doesn’t smooth yaw motion.