Of course this is the rule for the companion ticket but not for the SEN/HON member ticket.

The M&M website is even more clear:
"Where a Companion Award is used, the HON Circle Member or Senator cardholder and the companion must travel together."
The same in German:
"Bei einem Companion Ticket müssen der HON Circle Member oder Senator Karteninhaber und die begleitende Person (Companion) die Reise gemeinsam durchführen."

My last trip that way was in 12/10. I never had to ask for an exception and nothing has changed with the T&C wording.