Well the only other way to run it is to attach to a soil line and a vent line. Which may mean you would have to break up the floor and find an appropriate drain. Then you might have to break up a wall upstairs and tie in to an existing vent (every fixture has a drain that goes down and a vent that goes up). Each one is an integral part of the plumbing system. This is most likely why they used a small pump. Not such a bad idea, and perfectly legal.