Im not so sure that this was a rub ,I spent a little time reviewing the pics, and everything that I have seen looks to be an extreme freak accident or something else .
If you look closley at the pic's you'll start to see what I came up with (Wrong or Right )and I could be wrong!
1. Mature bucks (like the one in the photo)rarley make new rubs , but rather rerub what they rubed in previouse years or rerub trees that subordinate bucks in thier territory have rubed (saplings smaler trees ) rubs on larger trees are due to years of use, this is seen by the layers of scaring of bark .None of the pics show any sign of prevoiuse rubbing.
2.Pic 1 shows splintering of the wood around the brow tine , as if ther was a single hard inpact rather than rubbing, no where else is ther any splintering present.

3.Pic 2 shows a single inpact marks (above the rack on the tree)of the G1 and G2 tines (no rubbing).Given the center of inpact would be the center of the head or brow tine.

As far as coyotes or any other predator having any thing to do with this is deffinately out of the question.
The damage on the side of the animal was postmortom (after death)and caused more than 2 hours after the animal died,as there was no blood visable on the hide or the tree. As well coyotes will not usualy start to eat in this area of the animal,usualy its the hind quarters or the lower gut area(no bone-easy protien)infact the only time any scaviging animal or preditor will focus on an area that is so well protected by so many bones (ribs in this case) is when an animal has been woonded in this area or its the only area exposed to them (such as an area being exposed by snow.

4.Pic 3- the brisket apears to show blood in a linial line like a knife cut
but no blood any where else , and no sign of hair on the ground around the animal.

I would apreciate any feedback GOOD/BAD please no hard feelings , this is only what i see from the pics.