Orca15, I think you broke the story. Looks to me as though this just changed. Here's the pop-up if you click on "companion upgrades" when you sign in on delta.com and start to book:

Review the following rules carefully before you proceed:

As a Medallion® SkyMiles member, you can request an upgrade for yourself and a traveling companion provided you fly together on the same flights.
Your traveling companion's SkyMiles number is required before the upgrades can be requested. If your companion is not a SkyMiles member, enroll your companion now.
Upgrade requests for both passengers will be processed based on the upgrade time window of the passenger with a lower SkyMiles membership level.
Upgrades will be confirmed for both you and your traveling companion using the automated upgrade process based on seat availability, time before departure, fare class purchased, and the lower SkyMiles membership level in the reservation.
Companion upgrades are not valid for traveling companions, who are general SkyMiles members and are booked in the L, U, or T fare classes.
If you want to continue without a companion upgrade, click Start Over to go back, then uncheck the Request Upgrade checkbox and continue with your ticket purchase. Once your purchase is complete, call 800-323-2323, or the number on the back of your SkyMiles membership card, to request upgrades separately for each passenger in the reservation.