NSIS has nothing to do with the lot that own Winamp & it was a clearly defined "not part of the sale" as it has been OSS from early on around it's v1.0 iirc which was a long long time before Winamp was eventually sold.
I still think they should be using their own forum with an archive of the NSIS sub-forum to ensure that there's a clear distinction between them & the lot that now own Winamp (as there's no benefit for them to be keeping that forum running other than a trickle of ad revenue) but that's down to those that lead NSIS to decide upon.