Those lens mounts and internal framing in the body are a lot tougher than most people would guess. I've been watching pros sling a 80-200/f2.8 or 70-200/f2.8 over their shoulder for decades - granted usually with the lens facing directly down, but certainly mounted with the strap on the camera. (Just the camera, not both lens and camera.) I've done it myself MANY times - pretty much any time I am shooting at a race track, in fact. I wouldn't push things so far as to hold the lens out in shooting position whilst holding only the camera body, but common sense will stop that immediately: it is pretty darn hard to hold it that way.
As noted, you'll naturally switch from holding the camera to holding the lens as soon as you get into the situation where the tail is wagging the dog - as people have been doing since lenses got big enough to care about in the 1960s. For grins, find a picture of a Nikon F or F mounted on - "hiding behind" might be a better term - a 1200-1700/f5.6-8 AIS Zoom-Nikkor! (That lens weighs something on the order of 35 lbs, and was in the news recently in the coverage surrounding the new pope.)
_____ Brian... a bicoastal Nikonian and Team Member
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