My objection with the wording is it speaks of screwing the spoke into the nipple, which would make one think that the spoke has to be turned somehow, as a screw being screwed into a static nut.
I can imagine an inexperienced mechanic trying to twist a bladed, straight-pull spoke…
Would have been clearer to say that the nipple has to be screwed further onto the spoke.
Agree that the picture shows the nipple being loosened. I always deal with nipples looking from the outside of the rim, so clockwise from that perspective tightens the nipple.
I like the zip-tie-on-the-seatstay as wheel jig though.