The braindead logic you're trying to use. Grow up.
Luffy's statement was from an attack that was fired 50m away (eyeballing it)
We've calced it many times, it was like a dozen meters away
Naruto was in a building when the stuff happened
Not to mention that this feat was given as relativistic for Naruto
Let me explain the logic right
From what we have for Luffy (the anime as support), Luffy started reacting when the beam was close to his face
Using this alone would be calc stacking. Our rules say this
Hiding Calculations
Hiding calculations is the practice of trying to avoid calculating a feat in order to be able to use the result in another calculation. In other words it is the practice of trying to fool people into not noticing that calc stacking is being used.
This usually occurs if a feat is quantified per a rule of thumb instead of precisely calculated. A typical example would be a character dodging a bullet from a short distance being ranked as "Supersonic" and then using that ranking to calculate the speed of another character, whose speed one can compare to the former in some feat.
While it is acceptable to rank a character by such a self-evident feat without a calculation, one should keep in mind that the unwritten calculation is only skipped due to being trivial, but is still the justification for the ranking. Hence calc stacking will still be an issue for such feats.
And this (and the Naruto feats) would fall under this
The big support is Luffy saying that it's too slow. Luffy says that the attack is too slow, and in the manga he says it while it's passing his face.
Then Luffy, with canonically far better senses in every department, directly says that Kaidou's attack was too fast
Him saying a lightspeed attack was slow
A. Has nothing to do with distance, it has everything to do with speed, and him saying it's too slow means that the speed isn't an issue.
B. Confirms that his senses can react to light
C. Is confirmed that he can canonically react at close distances to light without any measurements of any kind
D. Can be scaleable to more advanced senses
AKA it's fine.
Unless Naruto comments on the speed saying it's something in his ballpark, then it's bad