What adds to the confusion is that there are 2 Bethesda's: There's Bethesda Softworks, the publisher of all the games, and Bethesda Game Studios, the developer of TES and Fallout 3.
There is also the fact of how prevelant Bethesda's name is being used regarding this game. I have seen many articles referring to it as Bethesda's upcoming game which while technically true since they are publishing is slightly misleading.
In addition it is likely also intentional on Bethesda's part. Not so much that they are trying to take credit but just the fact of how big a brand their name is. When you think about it there are probably many people who are interested in this game that wouldn't have looked twice at it if they hadn't seen Bethesda's name. Its basic marketing. What will draw more attention. A small barely know developer or a big name developer. It was the same reason that L.A. Noire was marketed as Rockstar's L.A. Noire despite being developed by Team Bondi.