I think the WWE wanted to siphon off some of the publicity as well. They must have figured, "Well... we don't really like how wrestling is portrayed in this, but when people think 'wrestling' - they think us... so we might as well get some benefit out of it."
As for the Oscars, they will be given out on February 22nd, a week after No Way Out. My guess is that Rourke won't make an appearance until the night after the Oscars, and I wouldn't be shocked if he showed up with the award in hand.