This makes no sense. How can you get sick based on the FOV?
Try cupping your hands next to your eyes (like a horse gets these eye-flaps, to keep it focused on the things in front of it when its on the road with a carriage) and try walking around a bit. You have to turn your head constantly instead of moving your eyes. Basically, a narrower FOV makes you move your head (ingame camera) more, potentially causing nausea.
I found this out by Googling for 3 minutes btw.
I have no problem with the current FOV but more options to customize the experience is always cool.