If you've already told authorities everything you know - what more can you tell them? If you've already hired investigators looking into the case, do you want to muddy the waters with too many?
I've seen this more with some of the unidentified/cold cases, but we've got some smart people here at WS. There's always a chance in reading something about your own case, it could spark and idea of something new, some new person, somewhere to look.
Also, just because we don't hear publicly that DB and JI are doing something, that does not mean that they are simply sitting at home doing nothing. They don't owe the public an accounting of how their time is spent or what they've done.
Again, I'd like to point out Tori Stafford's case. Her mother was drug through the mud for not acting how people expected the mother of a missing child to act - and yet, had absolutely nothing to do with her daughter's death.