The above method to force Safe Mode did not work for me. But I figured out another way to do it.
(I’m using Steam version) => (MSFS is NOT installed in the default location)<==
If I created my own running.lock file (empty file), and put it into
C:\Users(your name)\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalState
But MSFS would still NOT show the Save Mode option. Probably because the file running.lock was not valid (because it had been artificially created).
So I had to find where MSFS was putting the proper running.lock file and move it to the above location.
It turned out MSFS was putting running.lock here:
C:\Users(yourname)\AppData\Roaming\Microsoft Flight Simulator
So, I just move the running.lock file from there to the proper location way up above and now MSFS gives me the Safe Mode option.