I'm not sure what this variant is supposed to achieve. By the time you have your sixth factory, you're almost always going to have a promoted freighter in play, which you can never remove from the game. At that point 'If you don't have a freighter in play' will never apply.
It's mainly a patch over a hole I ran into in a solitaire game I played yesterday. Over the course of the game, I built all of 8 factories and no freighters (partially because I never saw the point and partially because I didn't have the time/money/spectral type).