I-PKN localizer is not designed to "transmit backwards." In my opinion, it's actually the normal backcourse of the I-PKN localizer antenna that sits on a 11000 ft mountain. Its only purpose is to serve as part of the missed approach procedure at KASE (and a departure procedure from KASE) . The front-course is not used because there is no airport, runway etc. associated with this localizer antenna's front-course. (It is essentially just a navaid sitting on a mountain)
When you fly a localizer backcourse signal in the opposite direction (like some missed approach procedures require after flying the front-course and then executing a missed approach) you are getting normal sensing.
The reason why the note on the plate states that I-PKN is "normal sensing" when flying its backcourse is to reinforce the fact that it is "normal sensing" and eliminate any confusion (which apparently is not always the case). Having a separate localizer antenna installed by itself away from an airport and serving solely as a missed approach navaid is unusual.