In my opinion, the Arkham show would have been the DCU's behind-the-scenes view of Gotham. I mean, after watching Sofia Falcone in Penguin, I really got curious about Arkham and thought this show would expose a new side of the DC Universe that hasn't been shown on the screen yet. There is almost no DC villain that isn't linked to Arkham in one way or another, so why not show us one of the roots to the city's villainy.
However, he also confirmed that Lanterns in a central character to the DCU and that events in the show have significant connection to the whole Universe, so I'm thrilled for it.