Well, if you look at the jink rule, it reads :
"A model with this special rule that has moved in its Movement phase gains a 5+ cover save untill the start of its next Movement phase. If a model with this special rule moves Flat Out or Turboboosts, it instead gains a 4+ cover save untill the start of its next movement phase"
So I'd say, if you didn't move you can't get the 4+ cover, because you didn't get the 5+ SO can't get the 4+ instead of it. You can still do the 0.1 nudge and get it though. But what could you possibly gain by remaining as good as stationary, not shooting and charging with a unit, just to get a 4+ coversave ? Someone explain that