A ruling could have been made in your favor with the aim of not punishing you for an inadvertent infraction of the rules governing the use of clocks, but I'm not sure that's relevant. You made a hasty play, and nearly the same thing could have happened in an unclocked match if you had moved your checker from the bar to your five point, picked up your dice, and then picked up your opponent's checker.
You may also have claimed that your move was "impossible," but I think your move was illegal but not "impossible." You played 20/5, instead of bar/20* 20/15 15/10 10/5. The resulting position was not impossible. The current ABT Rule 4.8 allows your opponent to condone all illegal plays. I think it's an unsatisfactory rule. I think it's so obviously unsatisfactory, to most players, that I wonder why it hasn't been changed.
I wonder if your pre-ruling discussion included reference to ABT Rule 4.3 which says in part: "Checkers must be reentered from the bar before moving any other checker." One could argue that you did not do that, since only bar/20* does, and one could argue that you must do that, regardless of what your opponent would like you to do. But you didn't move "any other checker." So that's probably just another rule that needs rewriting.
And then I wonder if — given the current ABT rule — you would feel exactly the same about your opponent's action and the ruling if the position had been this instead:
The score is: Opponent 8, You 8 (match to 11 points). You to play 5-5
| Opponent | 79 | ||
|---|---|---|---|
                         | |||
| You | 109 | ||
| Position ID: t50hMACH3sYAQA Match ID: UYl2AYAAQAAE | |||
In your position, it could also be argued that it was clear from the speed in which you picked up your opponent's checker, unfortunately still after your turn, that you had intended to hit. It seems to me that your intention was clear, despite your procedural error, and a ruling in your favor could have been made for this reason.
A ruling also might have been made in your favor because the way you "bounced my checker in and around the board" made it clear that you obviously intended to land on the 20 point, hitting the blot there.
However, I would have ruled in your favor simply because not to do so offends my sense of fair play. A couple of years ago I compiled a list of situations in which — even in a tournament using the current ABA rule which allows an opponent to condone illegal moves — I would not allow a player to condone an illegal move. Below, I add your situation to my list.
You put your own checker on the bar, instead of bearing it off.
You put your opponent's checker off the board, instead of bearing your checker off.
You played your opponent's checker from the bar to the board, instead of bringing in your own checker.
You hit and picked up a checker, but placed it off the board, not on the bar.
You hit and picked up a checker, and placed it on the bar, but it falls onto a point, or you inadvertently placed it on the board but not on the bar.
You moved your opponent's checker(s), instead of your own.
On your turn, you hit the clock without rolling when it was possible for you to play one or more rolls.
You put a checker on the bar that was not hit.
You removed from the board a checker that could not be borne off legally.
You removed from the bar a checker that could not enter legally.
You tapped an opposing checker, indicating a hit, but neglect to pick up the checker before ending your turn.
You did not move at all when there was a legal play.
Added 2013: You enter a checker from the bar with a forced hit, but neglect to place your opponent's checker on the bar.
But the list of exceptions grows. Enough already — why do you all still play in tournaments that don't require legal moves? Why do a few tournament leaders run tournaments with stupid and divisive rules? Inertia, I think.