If I understand the nonrev policies correctly, employees are entitled to seats not occupied , whatever the reason may be. The two issues here seem unrelated.
Delta may not make high coach fares eligible for upgrade. So what? If I want to sit in business, I will buy a business class seat. You guys just need to stop blaming employees for using their benefits. And I agree with the above poster. If your company does not provide you with J travel, find one that will.