@Tes yeux noirs,
"or (most likely) are just what in Britain we call "knobs". Crashingly bad manners to keep the hood up when a guest at someone's dinner table."
Couldn't agree more.
Hats/headware off indoors, unless there is a religious or medical reason.
Anyone who sits at someone else's table, formal or informal, with a hood up, is an ignorant twat and should be treated as such, please or offend.
It is they who are greatly offending by their rudeness in the first place, and I would simply be responding to that rudeness.
If they took offence to me reacting adversely to their rudeness to me as host, then they may decide never to visit my table again.