[greymule]

If we're going to apply abandonment to any runner who retreats back down the 1B line, then we're going to have to call an out on this play:

BR bunts and reaches 1B safely, but somebody says, "Foul ball, right ump?" BR then leaves 1B and takes a few steps down the 1B line. The coach then says, "Get back. It was fair." So BR returns to 1B before the defense can play on him.

Would anyone call the runner out for abandonment on that play? I wouldn't, even though he did momentarily abandon the base. In fact, I've seen a variation of that play a hundred times. Never saw abandonment called.

But, with BR down the line toward home, if the defense did play on him, could they simply throw to 1B before he got back, or would they have to tag him?

Absent a ruling, I'll go with the "reinstated force" theory. The BR has to get to first, whether we interpret his presence in the batter's box as "occupying" home or not.