There is an RNAV GPS Approach available for R28L
They could have programmed the FMC and followed LNAV VNAV right down to the runway if they had wanted to
The chart I have seen is based on the original threshold, not the displaced threshold - so it is possible that the approach is not available. Adjusting RNAV approaches for displaced thresholds is problematic, as the waypoint positions & database coding have to be changed.