I believe the majority of posters on this thread are shocked by a decision to do the loop that the couple chose to do. But LE has JG's electronic planning map for evidence that that's what he intended.
@MrsEmmaPeel has provided a comparative map from the same app ^^^. It can be presumed that the couple was executing JG's plan, since there was evidence they went down one trail and were heading up another. The only way they could make that happen is if they hiked upstream along the river, just as their pre-planning anticipated they would.
Yes unfathomable. But, per LE, that's what happened. There's not a lot of room to argue with the evidence. LE did a thorough and sensitive job.