I don't see that "other runners return to the last base legally touched unless they were affected by the OBS" equates to "all runners shall advance, without liability to be put out, to the bases they would have reached, in the umpire’s judgment, if there had been no obstruction." Is there an interpretation that says that the latter language (from OBR and from Little League, which is all that I do) should be implemented in accordance with the former language? Note, for example, that the batter/runner in this play was well on his way to 2B, and one could imagine a play where say the batter/runner was barely short of the base at the time of the obstruction.