First of all, they're not removing the content, it's still available from the artist's page. Second, it seems to be based upon the conduct of the artist more than the content of the songs themselves.
In the R. Kelly case, that is true. I clicked into the linked policy and read that before reading the rest of the article. Spotify says, "That’s why we do not permit hate content on Spotify, and remove it whenever we find it."
The policy is aimed just as much at content as it is at artists.
The policy is aimed just as much at content as it is at artists.
Edit: This is the policy https://artists.spotify.com/faq/policies#hate-content-and-ha...