That call to STOPRATE was there to zero out attitude rate commands at the moment the astronaut switches into the semimanual final descent program P66. It was removed in the final few revisions before the first, unflown release of the Apollo 14 software (Luminary 163 [1]) because it was preventing attitude control of the spacecraft when Rate-Of-Descent commands were skipped [2]. Skipping ROD commands wasn't normal, but was something that was added as part of the effort to make the computer more cleanly handle large unexpected additional load, like happened in Apollo 11.
[1] https://github.com/virtualagc/virtualagc/blob/master/Luminar...
[2] http://www.ibiblio.org/apollo/Documents/LUM156_text.pdf -- look for PCN 1037