...when he was in uni.
He said the SOP for retrieving a stinky dead body was vicks vapour rub.
He has a small tube (like a mini toothpaste tube) he carried with him at all times.
When retrieving a rotting corpse he would wipe a thin line under his nose and proceed to work.
He said all the coroners/cops and funeral guys do this.
Besides it will help with your sinuses during the flight.
Or you could get the FA to have him removed, but thats kinda hard mid-flight.