You asked why did South Korea accept North Korean soldiers from Ukraine. The article says the soldiers requested to go to South Korea. But WHY did SK accept? My guess is they thought they were helping the soldiers by allowing them in.

Your previous comment asks why South Korea is so sensitive that the information leaked to North Korea. I don't want to ruin my chances of going to beautiful North Korea someday by saying something outlandish, but North Koreans can't go to South Korea because North Korea doesn't allow it. Additionally, these are soldiers who, if I had to guess, are not done serving in the North Korean army, or serving in Russia or wherever North Korea wants them to be. So now North Korea is going to open a dialogue with South Korea and demand their soldiers back. Now South Korea has to decide if they want to turn over these two men to North Korea, and if they don't this will be a diplomatic problem between two countries who are technically still at war.