[greymule]

I believe it was stated earlier in this thread. You can't have an out until you have an appeal. R2 went back and touched the base so it cannot be appealed. Once the runner has gone past the base, the runner is considered to have acquired it, and until upon proper appeal, is safe. The timing part is not relevant for a proper appeal once the runner went back and touched it.

No advantageous fourth out.

Well, I can see the logic of that argument, and you might well be right, but there's also logic that says you can't correct a miss after 3 are out, combined with the fact that the runner obviously attempted to correct his miss. To me that adds a wrinkle that makes this play not quite fit neatly into a black-and-white rule. I was wondering whether you had taken your question from a case play or a ruling. Apparently the BRD 2006 "discusses both possibilities."