I am not sure about that... I like the idea of a Silver Age Batman's game, but I always thought Arkham gameplay (combat and stealth mechanics) were heavily inspired in the animated series and I don't know if it would work well with that version of Batman.
I believe they meant the story would be a silver age story, nothing to do with the characters. Which the silver age story was an alien invasion and Batman and Superman rally all the other heroes. I doubt we're going to have a campy Batman game. It'll likely take the tone of Arkham series with its game play