I can totally see why Lowes is in on SBD Craftsman.
First: HD is heavily invested in TTI and Husky. HD has tons of Ryobi (TTI HD exclusive), Ridgid (TTI HD exclusive) and Milwaukee (TTI), as well as the majority of hand tool shelf space going to Husky (HD exclusive). HD doesn't seem to like SBD all that much. HD has totally or virtually eliminated the SBD brands of B&D, PC, Bostitch, Irwin, and Lenox. HD only carries an ok selection of Dewalt (because pros demand it) and Stanley (mostly in tape measures because they are highly regarded, especially Fat Max), a few other things and that's it. HD is highly dedicated to TTI/Husky as they have done a very good job building up most of those brands. One can see why they want to shut SBD Craftsman out.
Lowes on the other hand is practically an SBD house. Lowes carries full lines of SBD's B&D, PC, and Dewalt with lots of Irwin, and Stanley, even some Bostitch, they carry a Lenox tool chest for crying out loud. Lowes doesn't have much ground to protect on Kolbalt either. Kobalt does ok on the hand tool front, but nothing special (brand wise), and Kobalt power tools (their only house brand power tools) are a joke (brand and sales wise) compared to Ridgid and Ryobi.
SBD moving lots of Craftsman in to Lowes seems like a natural fit, especially seeing their tight relationship with SBD and their weakness on the store brands front.
Edit: Forgot to add HD has lots of Emipre and Hart, both TTI.