The above statement is actually true. The military power of NK is so hyped up by media when in fact, SK has much better military power. Think of it logically. On a scale of 100, NK's economic budget it 10, while SK is 100. So even if NK spends 90% of their budget on military while SK spends just 15%, it's NK:SK::9:15(even this is just an estimation).
But Seoul being close to the border is a huge disadvantage, as stated earlier. Honestly, NK has nothing to lose(compared to SK) by starting the war, it's SK that's gonna experience ridiculous amount of damage. Although NK will lose the war for sure, SK will have much much more civilian casualties and structural damage.
SK has to avoid the war at all cost.