Thanks for your post. You raise a really good point - what reasons could they have for not wanting to seek the public's help like they do in some other cases, where they give a press conference and are eager to get the word out to people?
The only thoughts I have why they are not communicating with the public as they usually would are that they either think if she was abducted (1) it was someone local and eventually they'll figure out who and don't need public help with investigating further within the close quarters of such a small town (and they've gotten too much public help in the past when hundreds of volunteers were out looking for her so they had trouble finding people at home to interview and called off the search), or (2) it was a serial sex offender and/or serial killer and the 15 person FBI team is carefully putting together a case that links other murders in the area to Mollie's disappearance. I don't like to think of either scenario, and hope she was not abducted, but maybe these are possibilities as to why LE has seemed to be so "mum is the word" on her disappearance.