I'm sure it is modeled in Black Shark. In fact I think it's modeled in FC2, although 6DoF isn't so you can't really tell. I'm sure I remember something about FC2 mentioning that the HUD is focussed to infinity.
When I first saw it happening, it confused me, but it struck me as something that was designed to work that way, and I'd just have to get used to it. I think zooming/changing the FOV makes best sense if you find it hard to read. I know some find that unrealistic as you can't change your FOV in real life, but your real life vision isn't subjected to the limitations of a monitor/tv.