Where's Wertham when you need him? This is almost like that picture of the severed-head and ax that he raised all the fuss with.
Actually, it's closer to the "injury to the eye" panel that got Jack Cole into Wertham's book (can't find it to include here...it's a close-up of a screaming girl about to get an ice pick pushed into her eye).
This image, like Cole's, derives its power from what seems ready to happen, rather than anything that already has. As Brainiac44 says, we will likely not see Aquaman de-brained, or even cut, in the next issue, but in the meantime we're left to conjure up all sorts of horrific mental images of precisely those things happening. And that, in its way, may make this kind of image more disturbing, more horrific and yes, more pornographic than if they actually followed through.
I also agree with what (I think) Brainiac44 is saying about Ross' art. It's so realistic that you can't get away with things you might in a more "cartoony" style. If Curt Swan had drawn it...which I doubt he would've...I don't think we'd find it so jarring. (And lest that come off somehow as praise for Ross, let me make clear I do
not think Ross' brand of hyper-realism is at all suited to the comics medium.)
Still and all, Braniac is a kindly uncle compared to Ross' version of Bizarro...he's been remade into something from a Romero film. I have to say, really, that I get less enamored of Alex Ross with every passing month. At least with Neal Adams it took me 30 years to lose interest...