In an interview with comic book outlet BleedingCool.com, Moore explained that an agreement was made that Steve Moore's name was not to be used in connection with the film's marketing as he was upset with compromises that were made over the course of working with Radical Comics on the series.
One of the complaints was that Steve Moore would not receive any compensation for the film, as the clause in his contract with Radical regarding that compensation, which was featured in earlier drafts, had been removed in the final version that he signed.
The problem is that after Steve Moore's death this past March, his name began appearing in promotional material for the film, despite his wishes.
Alan Moore, who has long fought for creator rights in the comic book world, was mentored by Steve Moore.
The Hollywood Reporter picked up the story, which you can read at this link.