Yes, that’s correct. Although you have selected a route, the Saver Day Pass is valid for the entire rail network (except mountain railways). Thus, you are welcome to travel with your Saver Day Pass from Geneva as well.
The entry of a starting and end point during the ticket purchase is required is needed for the ticketing system to evaluate the best ticket offer based on the distance between the two points.
Keep in mind that the SDP, as any e-ticket, requires your passport, or your state ID card, or your driving licence during the ticket check. A copy or a photo of your document is not accepted.
Have a great vacation, the snow is now definitely arriving this weekend.