Well somehow he's been shown to be alive. I don't know how, I'm assuming they'll explain that to us.
Considering how Clone Wars has a very good track record, I'll give them a chance to somehow explain this one to us, but I have the George Lucas Beatdown Bat at the ready. Always have it nearby for when he decides to retcon stupid shit.
I wonder if Maul is as free to Force Lightning as Savage Oppress is.