I think he has already established that he has the ability to do it properly and has set up an established technique to ensure a solid hit. He has also explained that he is doing more "deer shooting" than hunting. The rifle used is specialized to be sure and that is the particular challenge he has chosen to take. If he does so with skill and obtains clean kills then so be it. No different than shooting groundhogs at long range.

It isn't my bag either but hey I would love to take a few long shots and see what happens on paper. If I had the skill and equipment to do it consistently on deer then I don't see anything wrong with it. The key issue being skill and equipment. If he can get 9 out of ten inside the kill zone in varying conditions then I would say he is within ethical boundaries. I have seen and missed deer well inside of 100 yards and consider myself to be a pretty good shot. Anyone can miss, at short range or long regardless of skill. The possibilites for a miss at longer ranges certainly go up but i'll bet a miss at that range for most people would likely never hit the deer at all. Like I said not my bag for deer but who is to say a groundhog at 1000yds is more or less and animal than any other.