The site reports they heard rumors of this casting move earlier in the week. Now the story has added validation from the latest issue of Production Weekly. Which states that, "the studio is interested in Christoph Waltz for the villian." The report also mentioned there has been an "undisclosed choice" made for the Aunt Mae role in the film.
It still isn't clear exactly what villain Waltz would play, although The Playlist reports the rumored villain will be The Lizard. We had previously reported back in June that Waltz's fellow Inglourious Basterds co-star Michael Fassbender was up for the same role. But he opted to star in X-Men: First Class instead, where he will play a younger Magneto.