I'd think the fork has oddly chamfered holes from the outside with the pivot pin staked into the chamfers and then ground to the final fork OD shape. There's no way to tell the assembly operations. Was the pin staked cold or hot and if not is it heat treated, which wouldn't make sense with a spring and locking ball on the drive square. I'd grind a little of the chrome off the pin and hit it with a file. If the file won't cut it you can't drill it without annealing anyhow, and how would you know what size to drill it. I don't think it's reparable, but If I was taking it apart, I'd grind/cut of saw through the drive square and try to push the two pin pieces out with a wedge. After that? Lots of questions about the pivot pin.