Unless things have changed recently, the CC&RG and Rock and Rail both jointly own the line from the crossing just east of the CC&RG (Santa Fe) depot to Parkdale.
UP, however, retained dispatching rights on the route. I also believe that UP still owns the CTC system.
Both railroads still contact the UP dispatcher for permission concerning any movement on the line.
I have no idea what UP might say about having Shays creep along at 5mph should they ever start putting trains through the Gorge again.
But it WOULD be interesting from a train watchers's perspective to see narrow gauge trains through the Gorge obeying a Class One dispatcher and CTC signals!