Wow. I wouldn't put much faith in a sanctioning body who's Case Book is so out of whack that it "has no merit", to the point that the umpires simply disregard it.
(And I was registered with NSA a couple of seasons and worked some of their tournaments. Never had the occassion to invoke an out on the Look Back Rule and was never instructed to call this any differently than the rest of the softball world.)
If a "tie goes to the runner"
.... then in this case I'd have to say that a tie goes to the interpretive guidelines issued by the sanctioning body for whom you are working games. Having not one, but two, separate Case Plays saying the ball is dead on a LBR violation is pretty strong evidence that it's not a "typo" or a "mistake"- it's what they really mean!
Just out of curiosity, what other glaring mistakes can be found in the NSA Case Book?