No Joke. I likewise have always practiced emergency descents with the quick-donning mask straight over the headset. Never a problem.
Record keepers may remember, and new flyers may be interested in some SOP history. Prior to the quick-donning mask, it was mandatory (where I worked) for the PF to fit the mask any time other pilot left the flight deck above FL350 . It remained policy until legislation caught up with the advantages of the new quick-donning technology.
I always put on a headset when the other pilot leaves the flightdeck at any flight level for a completely different reason.
TCAS RA. Think it through gentlemen. Can you speak through a handmike whilst using the same hand to meet an RA pitch command? Like kissing your own dick, it is impossible.