Very clever. I'm guessing that the guy has a lathe with a rotating, multi-pin carriage stop and it inspired him to this design.

I've done something similar for production drilling of holes to several depths. Set the drill press depth stop for the deepest hole and make a couple of spacer blocks for the shallower holes. Stick one of the blocks between the stop and its seat when drilling the shallower holes.

A more elegant form of the "blocks" is cylinders cut to length and a half-diameter slot down the axis, said slot to fit over the threaded rod of the depth stop. Self-orients and stays in place better than a rectangular block. Once made, save the blocks; they can be useful elsewhere.