You are making stuff up here that you have zero proof of!
These people hired a PR firm to better utilize the media in the search for their daughter, now you see something sinister there as well.
PR firms are hired to help spread information, and to maximize the media's coverage to help bring attention to your case.
These parents are going through hell, and they are not very effective under the circumstances. They are getting class from every newspaper, television, radio, and magazine outlet in the nation, and they are in no shape to deal with this right now. On top of that, there seems to be at least one radio show host carving some notches on his gun with their suffering.
I'd get help too.
You assume that's the reason. If they were really so interested in finding their little girl, I would think they'd have been totally honest about all the details in the first place. Giving wrong information on how people got into their house could have misled police on likely suspects at the beginning. Rather than concentrate on their image with a PR firm, you'd think they'd hire detectives instead.