My guess is SK is told to act like they're upset, but they're not.
I think there are three possible reasons for hyping up North Korea helping Russia, all coming from the Ukrainian / NAFO crowd:
1 - Use it to push for official NATO troops in Ukraine, arguing since third party North Korea joined, NATO can too.
2 - Sell to Europe the idea that a bunch of Asians are on European soil, soil EU consider theirs because they consider Ukraine to be theirs, and evoke the racist in them, because Ukrainian Nazis are.
3 - Use it to rationalize losing, same way they use North Korean shells to rationalize how Russia did not, infact, run out of weapons, and if that implies NATO is weaker than North Korea, just don't think about it.