Yep - shoulder blade - steeper angle than he probably thought. If you've ever examined the shoulder blade of a deer, there is a spline of bone that splits it across its center to give it lateral strength. A broadhead hitting there at an angle will get poor, and often deflected penetration. I'm betting the deer will live, though its unlikely you will be able to confirm it.

I once hit a doe square on the spline of the shoulder blade, and only got about 6 inches of penetration - but the blood trail was immense, and she only went about 20 yds before falling. Upon inspection at butchering, the broadhead only passed about 2 or three inches through the bone, but with a sharp broadhead firmly embedded 2" into the lungs, every bound she made cut the lungs to shreds, and down she went. I'd say this did not happen in your buddy's situation.