I think the turtle is probably in no danger from a golf ball, but a mower or even a golf cart might be a different matter. Even so, I wouldn't get near a snapping turtle. I'm no expert, but the pointed rear edge of the shell makes me think that the one in the photo just could be a snapper.
So as something of a "city boy", I don't know what a snapping turtle looks like. I moved that little guy along and he just pulled into his shell and pee'd a bit. I expected the pee, and didn't get hit.