People bitching about MS misusing the term "open-source" are, IMO, ungrateful SOBs who have never attempted to implement a non-trivial algorithm based on nothing but a stack of academic papers.
For me, the greatest value in having the source is to learn from it, not to hijack it.
I think a lot of people appreciate the move MS made while simultaneously condemning them for their casual appropriation of a term having a well-established meaning. They've updated the blog post in the meantime, so this is a non-issue.
Resorting to ad-hominems does nothing to strengthen your argument, btw.
For me, the greatest value in having the source is to learn from it, not to hijack it.