The worst thing is that most modern MOT testers don't understand that a kingpin usually has a little play in it, (unless it's brand new), which looks a lot worse at the outside of the wheel. Modern ball joints don't have that play until they're worn out!
When I had vans with kingpins, I used to load the grease gun with the thickest grease I could find, and pump it in immediately before it went into the MOT station, and that was usually sufficient to get the pass