Naruto did not tell what he was going to do, he just said he have a jutsu which he has been secretly practicing even more than rasengan.
Sasuke asked if he was sure it is gonna work and naruto said he was sure about it.
If Kishimoto wanted to bring comedy into this chapter, he had to portray sasuke out of character. Just like in part 1 where they wanted to see what was behind kakashi's mask.
Kaguya froze in place long enough to get Hit by Naruto so way complain about success plus we found out Sakura is a closet pervert after all and the grief She gave Naruto over that Jutsu. what a Hypocrite.