You're stretching logic beyond the breaking point.
If you took over a job from someone who worked "off the clock" (during a paid break, an unpaid lunch, or before punching-in or after punching-out,) and you were being hauled in the office every day about your inability to do the job, I'm betting you would be citing the fact that Management is comparing apples to oranges. They are comparing you, who only works when you are suppose to, to that previous guy, who worked on the sly as well.
That previous guy was being dishonest. He just happened to be dishonest in UPS' favor. He was falsifying his time card regarding both money and hours worked even if he didn't realize it.
And if UPS is obligated to contribute to the pension and H&W funds based on paid hours like here in New England, then the funds are shorted $12.85 per week (based on fifty less minutes per week.)