It is coming from somewhere in and around the organization, but no 'official' channels. That's why you'll see certain posts carefully worded if there is no media source to link to. The site maintains a list of vetted insiders, and then mods from individual boards, like ours, can also allow those that haven't been vetted to post information if they've been proven to be reliable.
The thought is that the team will protect 5F/3D/1G in the upcoming expansion draft. Letang and Schultz will be protected, so that leaves the choice between Maatta and Dumo. Performance wise, Dumo fits the system better. Also, when he is re-signed it should be for less than Maatta is currently making, which with the cap projected to remain flat makes it more likely he'll be the third D. The team obviously doesn't want to lose Maatta for nothing, so he's the logical choice to move. That's the current thought, anyway. Things can and do change.