I don't see Hoke encouraging fighting; first and foremost it is simply the wrong thing to do and while Hoke makes many mistakes i don't think he is malicious. In addition, no coach wants a player to get hurt and a fight can get out of hand and result in players getting hurt. It makes no sense for any coach to risk that nor do I think Hoke is so callous to do so.
Finally, if the other team doesn't take the bait it can result in penalties for your team that could be very costly. Take LSU - Bama where a last second unsportsmanlike conduct penalty cost LSU the game when they had to go for a FG instead of a short run for a TD. Had the LSU player simply walked away LSU would have been on the 6 and probably would have punched it in and Bama would have needed a TD not a FG with less than a minute to play.