He had to go with Maleficent, because her castle is more well known. And plainly put... just badass looking. It makes for a perfect landmark for a villain park. In fact I can't even remember what the Evil Queen's castle even looks like.
I can't believe when Disney just lets things stay vacant. The Former Alien Encounter/Stitch attraction in Magic Kingdom has been rumored to be replaced for many moons. But still it remains vacant and unused in a prime location.