[Roll'nCircles]

Good observation! The Starfighter would not benefit from swept wings, the designer knew this (Kelly Johnson). The nose of the 104 is far enough out in front of the wing so that the shockwave coming off the nose at mach 2+ would not come near the wingtips (small straight wings that are far behind the nose)

So, there is no reason to sweep the wings on this design to keep them from flying through the shockwave - the shockwave that is coming off the nose of the aircraft.

As the aircraft flys faster and faster through Mach 1, the angle of the cone decreases bringing the shockwave closer to the aircraft structure - aka the wing.

hope that helps

Ever heard a 104 in flight? Its the most awesome sound ever!