I think that blurb by Leatherman, about MacGyver carried a leatherman in 1993 was meaning the actor himself carried it as a cycling tool, which I found a reference too, but he never used it on the show.
Edit: Ok you had me super curious on this one. I found a reference to a PST being used in season three.. but by the enemy chick trying to kill MacGyver, not by Mac. Very telling eh, the good guy using a SAK, the evil woman using a Leatherman!
I just confirmed it, I looked up the episode on netflix, here are some screen caps. She uses a PST to install some device in an electrical outlet.