No thats not the case. North Korean 7* coders cheat on regular basis. They solve everything in a team
For example :
(He (7* North Korean) got rank 1 by cheating, but got plagiarised in October Long,most probably cheated in other contests as well, but smart enough to change code properly)
@rns5 is his username, same college and university like @rns6 . Both guys seem to be the same guy, and always submit all solutions at last minute . (most probably use alt accounts for testing solutions).
Other times 7* north koreans cheated and got caught :
These 2 guys are the highest rated coders on Codechef from North Korea and they were caught cheating as well. Its very common in North Korea.
As they are 7* coders, its easy for them to change codes and most of the times, even discussing ideas with each other would workout for them.