I'm glad you're looking at criticism of the Princess and the Frog. I think that's a valid concern and worth discussing. As with all stories (including Song of the South), there are different factors that we should consider. For example, the intent of the creators vs. the effect of the film (I don't think Disney filmmakers were trying to promote racism, but I do think the film perpetuates racist ideas).
We should also consider how the film is received by audiences. In the case of Princess and the Frog, the film was an attempt to create a story that featured African American characters in a way African Americans could identify with while also appealing to the mass-market. In that regard, it seems to have been successful. Building on that success (of creating something that connects with an audience), it makes sense to me that Disney would choose it as a replacement/overlay for Splash Mountain.
Also, thematically, it probably won't take as much work to fit the style.
I'm all for discussion about the merits of the film!