The safety lever also cams the cocking piece to the rear and off of the trigger sear in the 'safe' position. So removing the pin still shouldn't allow bolt manipulation with the safety on IIRC.
The safety works in about the same manner as an SMLE safety with addition of the bolt lock pin.
I'd assume the bolt lock pin was added to take any stress off of the somewhat more fragile cam feature should the rifle take a hit/fall on the bolt handle with the safety on,,thinking from the military usage standpoint. Just my guess though.
The safety housing and the bolt handle form the 3rd lug (safety lug) for the bolt. There should be a small amount of clearance betw the back of the bolt handle and forward face of the bolt safety housing.
