I think that would depend on the content. One would have to examine each and every piece of software included to see if there were distribution limitations. The seller has conveniently put everything together in one place and is selling that as a service. It is also clearly marked that all of the contained material is public domain and thus free. I would consider paying someone a fee to put together a CD of public domain content that I was interested in. Is that illegal? I don't think so...
