The trades are the mouthpieces of the studios. Gunn tried to deny early reports that he was completely rebooting the DCEU, but in hindsight they were all true. They don't really report rumours, as they are directed towards other people working on the industry. At most there might be a situation where there are contradictory reports coming from two conflicting parties.
Of course, a movie that gets announced by the trades could not end up happening, but the same thing can happen with any of the movies Gunn himself announced (remember the 2014 DCEU slate?).