That's a good point, but Disney didn't buy Pixar, they just collaborated together. If Disney bought Marvel then chances are they're gonna put their name on it. I would think anything with their name on it that isn't kid friendly would ruin their image. I'm not saying they have an evil master plan to ruin Marvel, but most likely changes will be made.
Edit: I guess Disney did buy Pixar. I guess it still wouldn't matter though. I don't think I've ever seen anything bad come out of Pixar.