According to the FAA, we are
supposed to stay within Line Of Site at all times, or we can be considered operating in a reckless manner, and subject to FAR 91.13 and a $10,000 fine. See this thread about the FAA:
viewtopic.php?f=3&t=29815
I think the FAA lacks the manpower or will to enforce all but the most infamous events resulting from FPV BVR (beyond visual range) operation, so I think most pilots will be fine. On the other hand, following the rules isn't an awful idea either, but it kills a lot of fun.
The point is, DJI isn't worried about you getting disoriented when flying the inspire, since you
should be able to see it visually at all times. I know I have become disoriented flying FPV BVR on the Phantom, so I'd agree that trying it with the camera facing 120 degrees would be a very big challenge.