This is such a ridiculous accusation. Why do discussions about source-available models often turn into accusations of soliciting free labor? Why can't authors just provide access to source code, but reserve some or all of the distribution rights? It's their code, after all. Nobody is forcing 'the open source community' to contribute under the terms set forth; anybody who does contribute does so under their own free will, under the terms set forth by the license.
It doesn't always have to be a binary choice between open source and closed source, nor does it justify further accusations of "openwashing."
Fair Source is a better model in that regard, kudos for using that! And I personally have no problem with using the term “open source” for that, although just using the distinct term is better.
In case of Winamp though, they:
1. Used a crayon license that prohibited pretty much everything and was indeed focused on collaboration
2. Made a press release about “opening up” the source – not using the exact phrase “open source” (except in the URL: https://about.winamp.com/press/article/winamp-open-source-co...), but misleading nonetheless
3. Weren’t even the original authors
This is openwashing, and it is ridiculous, and they were rightfully shamed.