I think the bad sportsmanship part is worth removing as that should not be judged on in my opinion.
I think pinning is a simple thing to understand though. If a another robot is being held agains a wall or so then the attacking machine needs to back off to give some chance movement. With Tiberius we used to try and pin up the wall to get a good grip, then at 10s release and back off just enough that the other machine had the opportunity to move. This would only be say a second or so in which Tiberius would move to a different angle of the machine in order to get a better attack. Reversing 1.5m or to the middle of the arena seems too much to me. It's basically stating you need to seperate and have an even attack at each other again which I do t feel is fair.