This is insane. Can the Secretariat please give unambiguous advice
(preferably backed up by a letter from the Korean embassy) to attendees?
It sounds like you might be safest contacting the Korean embassy
yourself and asking for a visa. If they say you don't need one, you're
on firmer ground than if the IETF says you don't need one.
I would guess that the amount of "firmness" you get is probably the
same if you get an answer from the Secretariat, the Korean Consulate,
or your uncle Bob. Since it seems to be a grey area, the determining
factor will likely be the whim of the immigration official (who I
imagine will likely be unmoved by your claims that you talked to
the Consulate (how would they be able to verify that?)
--Ken