I am very inclined to say NG has this wrong. We've heard the LL and/or a neighbor (maybe one in the same) saw and carried on a convo with Lucas, and EG also said the LL came over on that date. Also, JH talked to Lucas on the 15th - and when LE first talked to him, I really don't think he believed there was a crime to cover up, and he wouldn't have lied because he really wanted Lucas to be found safe. If someone asks you questions on the 17th, about the 15th vs the 8th, you aren't going to mix those 2 days up because the 15th is far to close in time. I can see mixing up dates after a couple weeks have passed, or mixing up last Tuesday with last Wednesday, but you aren't going to be confused about something that happened 9 days ago vs 2 days ago.
Including the statement from LE that doesn't yet corroborate NG's statement, and the low likelihood of knowing a few days different in time of death after over 3 months in the elements, I'm going to call this pure rumor until we have a more verifiable source.