I am surprised by the answers. I myself use a normal length primary (short) and will donate the primary and whoever is the lucky recipient is just gonna have to stay close. My secondary is longer (standard octo length - whatever that is) and is routed under my arm and worn on a necklace.
The way I view it is.. the OP is putting his normal octo on his neck rather than clipped off on a D-ring. That is an improvement over the standard recreational rigging in my opinion. It may not be optimal in many people's opinion, but it is an improvement in my book.
It would be better that the recipient use the longer bungied secondary, but if not.. it is not that big of a deal in my opinion. I've had to share air in three actual emergencies underwater, and my configuration worked.