Silence from LE can mean they do not need help, or just the opposite. In Holly Bobo's case, there has not been a press conference of any note in a few years now. They won't even say which of her items were found and which remain missing. They seem to have no suspects or POI's, the reward is huge, and yet nothing happens. Not a word from LE. Her thread here has been closed, pending news, for many months now. There have been other cases where LE says little or nothing for months, and then asks for help, when memories have faded.
I am not convinced that LE even knows yet if a crime has been committed in Heather's case, with no crime scene, not even a real sense of where or when she was last known to be alive, other than that 3:41 entry and a possible video. If they saw anything in the video, it does not seem to have been anything to determine she was a crime victim.
Most people seem to assume she has been abducted but LE can't make assumptions, and IMO they seem to have very little evidence. If they had a POI, for example, but not enough to charge, they would likely be asking the community to help fill in missing details, IMO. At least I hope the would, rather than just hope evidence drops in their laps.