Well, I've been guilty of being Mr. Stinky on a flight or two many, many years ago.
Working in rendering plants in Iowa for days on end, then catching a plane back home.
No, a shower doesn't get rid of the smell.

I've since learned to 'excuse' someone's odor, as circumstances are not always such, that one can board the plane in 'pristine condition'.
What's much more appalling to me in OP's story is the person's attitude.