Dave, you've illustrated one of the more frustrating circumstances in one-pocket: when your opponent only needs one, and it's hanging in his pocket!
As you've discovered, there's no problem if there is no ball that he can neither make, nor legally shoot from the Kitchen, after you've made his hanger and followed it in with the CB.
For that reason, experienced players will take special care not to allow their opponent to be in the situation where they only need one. Oftentimes the opponent will need two, and have on hanging in the jaws. With the right lay, rather than just pocketing that ball, good players will follow it in with the CB so that the opponent will still need two-- even though the shooter owes a ball.
But when you're faced with that situation where he can easily get out after you've scratched, then you have no choice but to shoot at a flyer or other difficult shot to your own hole, and hope that it goes in! When that situation comes up, take your best shot. If you miss, pay him off, and move on to the next game.
Doc