Here's the full article
http://www.msnbc.com/news/981625.asp
I don't think they have a physical impediment in the first place. It all depends on your enviroment. If you grow up in Korea, you're going to have an accent. Your parents give you an accent. Your native language gives you an accent.
However, I knew some Koreans at my school who spoke flawless English. Why? Because they were born here. It has nothing to do with how the tongue is shaped. People all over the world have different tongues and can master their own language easily. The body adapts. You can always lose an accent, but it takes time and work.
I was alarmed by this article because I thought they snipped the TIP of the tongue until I re-read it.
Of COURSE a six-year old has a short frenulum. He's barely developed!