I see the release notes of DS6.9 SP6 now in the correct place in the knowledge database; thanks.
The supportability matrix you mentioned is for 7.5; has nothing to do with DS6.9 SP6.
I see that the release notes in chapter 'General installation and upgrade information' has been updated; versioning at the beginning of the document would enhance the readability.
It now states that WinPE 4.0 is incompatible with Windows 2003 as a platform for DS.
However, this is not a replacement for a supportability matrix; for instance, it does not mention if Windows 2012 is supported as platform for DS and/or which SQL versions are supported.