It would sure appear to me that there should be no difference in the treatment of offense and defense in this type of situation. If we're going to call the BR/runner out if they make contact with a ball that "appears" to be rolling toward fair territory, then you must award the base to the BR on the bunt/batted ball rolling down the chalk line that slips into foul territory and is immediately grabbed/slapped/touched by the defense. There is no discernible difference in my mind. Be consistent, gentlemen, that's all we're asked to be.
By the way, John
, the "implication" is in the book, but the "inferrence" is being made by all of us.