Conditions were not easy on a breezy morning, but Choi at least beat the worst of the weather to post a five-under 137 halfway total before play was suspended.
Half the field completed the round before torrential rain halted competition just before 3 p.m. First round joint leader Matt Kuchar was among those forced off the course.
"I'm very happy finishing before the rain," Choi told PGATour.com. "Even in the morning it's very tough, wind blowing. Today the putting, I make a lot."
Choi, 43, has won seven times on the PGA Tour, though only once since 2008.
His halfway score was two shots better than Englishman Luke Donald (69) and Americans Billy Hurley (69) and Scott Langley
(73).
Former world number one Donald is ideally suited to the tight Harbour Town course, where precision is more important than power.
He has a remarkable record, albeit without winning, having finished second or third four times in the past five years.
"If I'd got hot with the putter it could have been really special but still a very solid round and glad I'm done (because it) looks like the weather is only going to get worse," said Donald.
"You've got to keep it in play and plot your way around this course. That's why I've had some success here.
"It's not a course you can overpower and you need to be proficient around the greens. I hit 15 greens and with these small greens it's a job well done."
As the late starters bid their time waiting for the rain to pass, the PGA Tour predicted that action would resume later in the day.
"The golf course was probably playable (but) it wasn't going to take very long to go under," tournament rules director Slugger White told Golf Channel when asked why play had been halted.
"Conditions were horrendous. We had probably 35 mph winds and the rain coming sideways."
(Reporting By Andrew Both in Cary, North Carolina, editing by Gene Cherry)
