True, although the article didn't seem to be pushing for people to fork FirefoxOS into IceCatOS or something but rather going with FirefoxOS. I would rather Mozilla change their trademark policy so as to preserve freedom 2 instead of forking. For the others, they are their own independent free standing distros. They may pull in software from other places but then so does practically every other distro. Trisquel, for example, maintains things they call Helpers to make changes to the programs that they pull in (which come from places other than just Ubuntu.) They also make it work better by improving accessibility by replacing accessiblity-poor programs used by upstream with different ones (accessibility being an important thing for the project), adding or turning on privacy-enhancing things, writing new programs, and etc (The exact nature and extent of everything that's done can be found in the public git repository.) Characterizing these distros as simply "X with the non-free stuff removed" makes it seem like something rote and seems to discount all of the other work that's done as well.