No, union rights in general are under ******. The Republicans are trying to (and in some cases succeeding) pass laws which, among other factors, prohibit private unions from collecting dues (Michigan's "Right-to-Work" for instance).
How does removing the bottom rung and making it possible to pay wages that people can't live off of it, and thus lowering the entry point for the competition, widen the spectrum? It doesn't. It makes a new low, and lowers the need to compete above thus lessening the whole because, as you said, this is business and no one is running a charity and thus they aren't paying more than they have to in order to be competitive. Your own logic derails your stance.