Even then, RMS has no problem people selling and buying software, he only cares that, once a user has acquired the software product, he can alter it (that's the "free as in freedom" part, as opposed to "free as in beer" which RMS — as far as I know — doesn't really care for).

Now building a business with these constraint is not — as far as I know — a solved business model in the general case, but saying that RMS wants developers to "give their product for free" is a complete and absolute misrepresentation of his position.