Please disregard my Haunted Mansion comparison if it doesn't hold for you. My post still works without it.
No, it would be like saying that there would be no Disney theme-park attractions based on those stories had Disney not made film adaptations of them first. Splash Mountain's current theming would not have happened without the existence of Song of the South.
How exactly is a log-flume ride the appropriate context in which to educate people about anything? What would "set[ting] the record straight" entail from your perspective?
Defend them on what point? Their decision to retheme the attraction, or their reluctance to revisit Song of the South? As regards the former, I don't so much defend it as understand it. I'm on record as saying that I love Splash Mountain in its current form and will be personally sad to see it go, but I also get why they're doing what they're doing and am excited to see the outcome. As for the latter, I don't think Disney has much to gain by trying to address or correct the wrongs of Song of the South, nor do I think they could succeed in such a project, though that's a debate for another thread anyway.
I don't understand what wrong you're referring to.