I never said he should offer a "sip." I was actually thinking more along the lines of a Big Gulp!
I have never been to Korea, and have only known one person who has lived in Korea. In most of the other countries in the Far East, though, social drinking is important; declining to participate when the toasts begin is considered a great insult. In China, a formal dinner among higher government officials, or business associates, the toasts will start before dinner, continue throughout dinner, and continue for another hour or two after dinner. My partner was there last fall, on official US government business, and he told me they nearly pickled him.