if I may, since it was my pic. Pinning a grip safety on a 1911 was popular years ago because Cooper said it was worthless and should be deactivated. There are several ways to deactivate it and one is pinning.
There are a few ways to pin it as well. I have done a few different things. In This sample an EGW (thick walls at the hump) grip safety was fitted. Then compressed against the internal frame stop location with the mainspring housing in place and mounted to the rotary table. After measurements, a hole was drilled through the frame and three quarters depth into the grip safety (a blind hole). Then a slip fit piece of drill rod is cut to length so that the grip safety can be locked into the deactivated position. The grip panel then holds this pin in place. Simply remove grip panel and drop out pin to restore the function of the grip safety.