Originally Posted by rylan

I wouldn't necessarily say that DL is strict about the primary being on the plane without some recent evidence. I don't recall seeing any stories or reports about this scenario in quite a while... usually its the reverse and that is no issue if the companion is a no-show.

In this case since the primary would've already flown the outbound I think there is a lot less risk, and the ticket would probably not have any value left anyway.