Naruto vs Delta
Because the writers did something stupid, and then tried to explain by some half-ass reason.
Naruto should be able to easily beat Delta with normal sage mode. But the writers made him use Six Paths to show “oh nooo look this Kara thing is really dangerous” and when they got so much backlash for that, they came up with the Naruto was actually holding back stuff.
I think they said it was because naruto was hoping delta would talk a bit more but really it would have been easeir for him to capture her and then they interrogate her in the leaf. Naruto should have been able to easily win that fight even without the six path sage mode
there was no good reason for him to do that, the authors just said that to try and make some sense of that stupidity.
I don’t see why doing that would be good for him, especially since there might be other enemies around and his kids were right there.