Obstruction Scrambling Back?

[BigUmp56]

Runner advances to homeplate where there's a close play, however he misses the plate on the slide. The ball was misplayed by F2 and deflected a short distance away where F1 backing up the play picks the ball up. The runner scrambles back to touch the plate and while doing so collides with F2 before the touch. F1 applies the tag before the touch. It seems like a clear case of obstruction to me, but the umpires concluded that obstruction cannot occur after a runner has passed the plate. Is there any interpretation that would substantiate their claim?



Tim.