So the bottom line answer is "yes" - at least for the first time, and certainly for oil pump removal for inspection? I will also look into fabricating a special socket tool that might fit between the mast and crank pulley.
Eddie, If you Google Subaru Low Idle Oil Pressure "screws" (the quotes indicate "screws" is a required term) you will find six examples, including some YouTube videos, where the oil pump had internal screws backing out. Granted these are not "Gyro" incidences, but I think it warrants an inspection. Just imagine all the times it was this issue, but not reported on the many Subaru threads nor YouTube! I have received nothing further from other RAF or Subaru gyro owner operators. I may find nothing wrong, but I am at least going to take a look.