We have heard before of possible rumor clampdowns because of leaks, and because of legal problems with other modelling companies quickly releasing models to fill in gaps left by Games Workshop. This one takes the rumor clamp down a little further, and in my opinion looks more like an excuse (pointing fingers somewhere else) than anything based on reality. It may have some partial truths to it though, so take a look.
Please remember that this is only a rumored reason for such a tight seal on rumors coming from Games Workshop. Please take with salt.
At the Las Vegas Throne of Skulls, staff and regional reps stated the lockdown is due to one thing.
That was what was stated in a Q&A they had at the end of the tournament. When GW re-upped their license to cover the new movie, they were forced to accept a one week info window. The design studio has had full access to scenes and images from the new movie. MGM does not want any info released early on the movie and required GW to demonstrate they can keep a fairly tight lid on info and images coming out of the studio. No one at GW likes it, but given how much money LotR made for them, they decided it was worth it. Any money loss due to reduced subscriptions or sales would be more than made up for with the Hobbit license.
Expect this format to stay around for at least two more years. Once the second Hobbit movie comes out, hopefully this silliness will end.