Not for blood, no. Nor for scorn. If Batman is to be Talia's husband and most likely Ra's heir, then he can't have things such as the Justice League in his life. Such ties would inhibit him on his quest for true justice. So kill the Justice League using the Batman's very own paranoia. Heck, this may be why Lord mind controls Superman. To make Batman think that Big Blue has gone rouge, thus proving that he can't trust the League.
That is just an idea though.
One way this movie can distinguish itself from Nolans...pronounce Ra's name correctly ("rae-sh" and not "roz")