Yes, but that's not the (controversial) claim in the article, the claim is that you can't upgrade without reverse-engineering the new database schema yourself. The article doesn't really address the issue of a plugin not being available as Free software. While FSF/RMS doesn't particularly like closed source software of any kind (it interferes with the four freedoms), this article deals more with Free software that is hemmed in by various "external" constraints. Data migration being the example referred to. And, which I perhaps was unclear that I was referring to, when I paraphrased: "used to do this, but we don't any more".