If your flight is delayed, the Supersaver tickets becomes invalid and you must buy a new ticket. Supersaver tickets are only valid for the selected connection and train. The only exception is made, if the previous train was late. In this case you are allowed to take the next possible connection. But this exception is not applicable to flight delays.
When arriving by air, it is not recommended to travel with Supersaver tickets. Instead, I suggest buying a regular point-to-point ticket or a Saver Day Pass which are both valid the entire day and for any connection.