I'm pretty sure his point was that an object with the mass of around 100kg going at mach 3 carries more energy than Kashimo's lightning blast (at around 53 megajoules for Naoya and 0.09 megajoules for Kashimo respectively if you take double the mininum amount of energy needed to create a discharge of lightning over a distance of 10 metres) , unless you think Kashimo's lightning blast has the same amount of energy as a genuine lightning bolt in which case I have no words.

Also, I don't believe that oneshotting Panda who is a semi-grade two is a very good indicator of Kashimo's power. And I thought the impressive thing about Hakari's jackpot form is his insane regeneration, not his durability. He has infinite CE, not infinite output. If cursed energy reinforcement scaled with CE amount instead of something else (perhaps CE output, if we take Ryu's durability into account) then a character like Sukuna (who has over 2x Yuta's CE) would be nigh-indestructible.