They already had that battle a couple of years ago. Since Patreon is seen as a tip jar and the end result is to be released for free, all DC/ Warner Bros. could do is request the name being changed to something other than "Injustice Unlimited". Hence why it's "Something Unlimited". So while parody is transformative (even though DC has tried to get pretty risky) the real thing that won GG the case was the intent of the end result to be released for free.
An unfinished work can be declared a violation of copyright law, but since none of the Patreons are forced into pledging, and this is all at the will of the creator, then the proceeds are seen as donation and not "for-profit". If the game were finished and being sold for money that would be for profit and violation. While many professional coders could make the argument that version 2.xxx is the designation for the second version of a finished product, GG has wisely put a screen at the game's start saying "work in progress".
tl;dr Been there, done that, got away scott free, its a game being played in the gray areas of the law rn.