The RSUs did help the company because:
1) They only paid out 20% of what was due to a management person in a given year, unlike the previous MIP plan, where a person got the right to receive all their stock when the MIP was awarded. It also allowed the company not to actually pay the entire money awarded until the 5 yr. period had passed, thus saving wages in the current fiscal years.
2) If a management person quits, then they forfeit all the retained RSUs that they had coming to them. It helps retention, because there is financial pain (lost RSUs) that occurs with the decision to quit.
In the past, most management people that were planning to quit would wait until December, get their MIP stock award, and then quit. Since they received all their stock, there was no loss in quitting. Now, if someone quits, they give up the retained RSUs. The company lost a management person, but gained not having to pay all the retained MIP. If management turnover is 5%, that's a substantial sum of money that is never paid out by UPS.
The one exception made is management people that leave UPS by retirement. If there was not an exception for retirement, then the plan would not include any way for a person to actually receive all the money that they had earned. That's why the company continues to pay a retired management person their 20% a year during the first five years after retirement.