Naruto manifested a chakra arm to block it because blocking is better than tanking it. That's obviously not evidence that his Katon is strong enough to hurt Naruto. Lmao.
There was some BS in this chapter, but this obviously isn't part of it.
I didn't say that Gokakyuu can hurt RBSM Naruto, but he leveled from base to that state which is the point. Teen Naruto had some durability feats before the Rikudou powerup, and after it he survived a fall from the... stratosphere? A ****ing high place, though someone may argue he still had some portion of the avatar along him during a part of the fall. Sasuke, who's physical attributes are on Naruto's level, was presumably hit by DRG JJ Madara's Limbo and wasn't even bruised. If he resorted to an upper state only when he was attacked it's evident he could have been hurt by the Katon.
Even by logically scaling, the Rikudou boost is huuuuuuuge (Chidori went from building level to small meteor level). That damage the onion suffered is something i should be expecting by an ordinary Katon, not the strongest from a demi god (and Pre Rikudou powerup Sasuke wasn't a fodder at using Katons). I doubt Adult Sasuke's Gokakyuu is weaker than Edo Madara's Gouka Mekkyaku. Now that i noticed it didn't even melt Kid Shin's kunai. That can't be his full power man, unless that shit is made of adamantium or something.