It would be important if either of the girls were expected to testify at DM's trial. However, I remember reading somewhere that DM was expected to plead guilty just the day before the girls went missing. Apparently, he requested a jury trial at that time (just the day before).
True, but he also had 2 accomplices who had pre trial meetings on that same day. Perhaps the girls were supposed to testify against the accomplices as part of his guilty plea deal.