I spoke to a very confident sounding DM agent today who claimed DL is doing a soft rollout of this new upgrade policy today, where companions in the same PNR clear at the higher status level.
She said she was told that if the soft rollout goes well, they will then officially push the change to the website and announce it.
Please don't crucify the messenger...just reporting what I was told as I was about to book a cross country and was inquiring about at least getting preferred seating for my companion at booking.