The director did go to South Korea, there is video of him in a south Korean market somewhere.
Obviously, a director doesn't cede his/her creative choices when doing post-production work overseas . . . which has been happening for a while in Hollywood. Post production work overseas is cheap, and is frequently done on many films.
If you haven't worked in the biz then you might not know this . . .
"The "Kill Bill" films relied heavily on the labor of offshore workers and overseas locations. Yet outsourcing is nothing new to Hollywood. Previous generations of Hollywood films have sent animation, visual effects, and post-production work to companies overseas. There is a new sense of crisis among American film industry workers, however, over "runaway productions" - films and TV shows that for economic reasons are shot wholly or almost wholly outside the U.S."
http://yaleglobal.yale.edu/content/hollowing-out-hollywood
"According to a 1999 study commissioned by the Directors Guild of America and the Screen Actors Guild, runaways have increased from 14 percent of total US film and television productions in 1990 to 27 percent in 1998. They have a total negative economic impact of over $10 billion a year. Today the practice has reached what the Los Angeles Times calls "epidemic" levels and involves many big-budget, high-profile pictures like the Academy-Award winning "Chicago"."
This article is about ten years old, and the problem of run-aways has gotten worse, IMHO.