LoL at people saying this proves the gaps are wrong in DB. Even assuming Vegeta was at just 18k (I think he was closer to 19-19.5k):
1. Goku had already lost a bit of energy prior to his KKx3 activation, which means that Goku's KKx3 was probably 24.000 (22-23k probably).
2. In the earth, the KKx3 dealt a lot of damage to Goku's body. That means that his strength started to fall as soon as he activated it, and also that he couldn't properly use that power due to the pain the technique was causing to him.
3. On the other hand, when Vegeta disintegrated Kiwi, he had already beaten him with two strong blows, which means that the Kiwi that was pulverised by the attack was weaker than 18.000