코앞이 북한! 최전방 끝판왕 공동경비구역 JSA 경비대대 밀착 취재! 최강 전투력을 유지하기 위한 실전 훈련 / 대성동 마을 / 판문점 (2008)

The "To be stationed in there a soldier had to be at least six feet tall and well versed in martial arts." is not correct or true, it is a myth. And a six foot Korean is rare.
A good friend of mine, a bit shorter than I am, was stationed there in 1980 and again in 1986. I am not six feet tall either and I was assigned there in 1994.

As far as the martial arts aspect. The Americans rarely if ever practiced any form of martial arts as part of their regular military training. As for the Koreans, there are two sides to the equation, were they KATUSA's or were they ROKA? If they were KATUSA, there martial arts expertise was not a consideration since they were probably average in their skill if they practiced at all. On the other hand for those that were ROKA, martial arts is a part of their military training and physical fitness regimen.