To be fair, there's plenty of racism in Tamriel and that's an undeniable fact. There are also legitimate reasons to dislike it, either as an in-game character or as the player. It's only a problem when people apply real world racism definitions to fictional, and very different from our world, Tamriel.
I don't quite see how the existence of Nord afterlife is racist... It's like saying "races exist, therefore TES is racist". Sovngarde is their culture, their belief, and that's okay. Besides, I think being a true Nord at heart is enough to get you a ticket to Sovngarde, you don't necessarily need Nord blood. That said, I can totally understand why people may be uncomfortable in Sovngarde. It's the same reason why some feel that only Nords are the 'right' race to be a Dragonborn - because the main quest revolves around Nordic history and their iconic ability, the thu'um. Visiting Nord heaven holds more significance for someone who hopes to go there after death. But I'm fine with being just a visitor.