I don't think your post contradicts morgante's point at all. As soon as you start taking your side project seriously, you stop being a developer (i.e. a person selling his or her time sitting in a cushy office) and become an entrepreneur. That means his developer advocacy stops applying to you and you become his potential competitor.

Of course there are different kinds of side projects. Everyone is worried about projects that could potentially grow into big businesses or popular open-source libraries. I don't think anyone will sue you over some inconsequential code written while being happily employed by Acme.