My understanding of the particular situation in question was that the player wasn't aware that his caddie that round had used the slope feature on his LRF until the caddie said something about an actual yardage versus playing yardage. At that point the player realized his caddie had been using the slope function on the range finder and reported it to a rules official, essentially DQ'ing himself from the tournament.
And although I'm not 100% certain, I think (?) the player was using a caddie that he wasn't overly familiar with, as in it wasn't his regular caddie.
But I could be mistaken.