The repository contains a README that contradicts the licensing information on the files themselves. The README then refers to a separate document that describes the actual terms, without making it explicit that it's referring to the standard Apache SGA (although I accept that that's the obvious conclusion). However, it then tells the reader to refer to an unavailable document for further information. It's reasonable for someone to assume that the files are under a license that permits the creation and distribution of derivative works, but it's also reasonable for someone to want some degree of certainty rather than relying on assumptions.
The SGA places conditions on the ASF, so I'm sceptical that it can be in effect without explicit agreement on the part of the ASF. I'm assuming that writing a significant body of racist invective, dropping it into a C file and then sending it to apache.org along with a signed SGA would not result in it automatically appearing in a subversion repository. You chose to accept this code, and in doing so you accepted that you would be taking responsibility for it.