Based on the fact that Karma Code was running away from Borushiki. And Eida admitted he can't deal with an opponent that powerful.
Plus, Borushiki was matching V2 Kawaki till Boruto woke up, while Karma Code by his own admission was getting utterly dominated by V2 Kawaki.
Naruto was referring to his chochoodama rasengan not his physical fight with Delta, a far weaker naruto's chochoodama rasengan annihilated fused momoshiki who was amped
If Naruto wanted to kill Delta, even physically, he would have used a series of
chakra arm smashes like the first that smashed apart her legs. Bro, Naruto was holding back a lot physically. He wanted the physical fight to be contained in a smaller area and to keep Delta's attention on him while looking for a way to take her down, as judged by Kawaki. The final Giant Rasengan is not the only time he held back.
The rasengan was Naruto's chakra amping Boruto's rasengan. And Boruto already strongly inherited Otsusuki powers, as vague as it sounds. I don't think the potency of that rasengan can just be measured as just Base Naruto's.
Delta would turn both Kinshiki and Base momoshiki into a kabob. base Momoshiki needed to amp himself with chakra pills to create a Bijuu dama that by Ssuke's own admission six paths naruto could have flicked away
Chakra pills are still a part of the arsenal of Base Momoshiki. I didn't bring up Kinshiki.
I was
comparing just their AP, not a fight. In my opinion, Base Momoshiki's AP is greater than Delta's. And if you are honest, none of Delta attacks knocked out Naruto like that bijuudama.
And in a fight, Fused Momoshiki > Borushiki > Karma Code > Delta > Base Momoshiki.