I don't understand how that could be. Wasn't LE on scene 24/7 starting at 11am on Sunday? If LE was on scene and "someone" not sure who would notice and report the decomp smell if it wasn't LE or Noah's parents. Why say hard and credible tip?
I strongly believe that someone called in and reported seeing something being done w/the septic tank which led to the discovery of his body. I really think that once LE opened up the timeline to include Saturday night, the tipster realized that what they saw was important. Whereas, prior to that and Ashley reportedly seeing him at 9:30am on Sunday the tipster didn't think what they saw was relevant.
IMO, JMO, etc