I cannot believe that touching the end off the barrel on any object doesn't affect barrel harmonics. That goes against all laws of physics. Any contact with the barrel at any point will affect POI of the bullet to some degree. I wouldn't trust doing this on any shot beyond 50 yards. And I that range I know I can put a bullet in a deer's vitals 10 times out of 10 offhand.
But the reason I believe Ron is practicing shooting offhand is twofold. One is to better himself and the other is to improve his shot chances at game. I've seen some of the pictures of the game he has taken and the terrain he hunts. Not much in the way of natural rests/supports. He has to rely on his own shooting sticks or take an offhand shot. Ron please correct me if I'm wrong.