Some tournaments penalize the loser if they rake the balls with the loss of that game plus the loss of another.
Not letting your opponent shoot an easy layout of a few balls does deny them the opportunity to stay in stroke, but I don't see that when you have only one ball hung in the hole.
Once I was playing in a nine ball Senior's tour tournament in Florida with a fellow by the name of Rick Bingham from Kentucky. I was struggling with my game and a bit frustrated with my level of play and while we were trading games back and forth and even at about 3/3, I jarred the nine ball, left it sitting on edge of the pocket and the cue was in the middle of the table and I said, "That's good Rick" and racked the next rack without letting Rick shoot the hung nine ball. Ricky showed me what class is when after I racked and before he broke, he walked over to me and discreetly and quietly told me that one of the rules in this tournament was that you can't concede any balls and that if you do, you lose not only that game but another as well. He confided that he just wanted to make sure I knew about the rule so no one else could call it on me. He made sure the tournament director nor anyone else was listening. I later confirmed what he said to be true and he will always have my admiration and respect as to how a gentleman should conduct himself.
On the other hand, I had a professional player call a foul on me recently when I was attempting to break a nine ball rack, when my cue tip touched the cue ball and moved it three inches forward of the headstring. IMHO, while it was the rule for that tournament, it wasn't a very classy move on the pros part, especially when he was playing a lowly amateur like myself. Pro's name will not be mentioned here as it woudn't benefit anyone.
JoeyA
P.S. I saw Corey rake the balls during the set as well when he didn't get shape on the 6 ball or maybe it was the five.