It's not being linked directly from the front page yet, but you can bet if they went to the trouble of making a separate bundle for it that it's coming soon.
Publishers have started to work out that bad Steam reviews are something to be avoided. Of course, they have no control over what the gaming public feels and writes -- and when they try to exercise some measure of control, through review manipulations or flagging negative reviews, it always backfires.
So what's the next step? To create a bundle on Steam that just contains the game you want to sell -- because that way, it doesn't show Steam reviews. After all, what if you wanted to bundle hundreds of things in the same package?
To their credit, Warner Bros aren't linking to the new bundle from the front page yet. The listing in Steam's featured items this morning goes directly to the individual game, where Arkham Knight's stellar 46% user rating is on full display.
You can't find this fancy new bundle (which contains just Arkham Knight) by searching for all Rocksteady or Warner Bros games, however. There's always the chance someone at WB created a new Steam entry just, well, because they could.
We'll wait and see how it plays out. Hopefully enough people notice and WB decide to cut their losses rather than trying something fancy to pick up a port of a game so dodgy that the developers have suggested having 12GB of RAM and a PC imported from Krypton to guarantee stability.