As much as I want to agree with this, my doubtful nature on chinese games kick in and found something sad.
I agree with
@ExcelsisBerny arguments on devouring as an ability and not an AP. This will prove why Devouring isn't AP.
Original chinese text for 5-B is here
The problem in first line is this word "仿佛" and this translate to "as if" which is completely left out in en localization.
This is crucial since this line can translate a bit differently with "仿佛"
It's not saying Narwhal can actually swallow the entire planet but the impression it gives off as a metaphor. In the first place, narwhal isn't even big enough to swallow the entire planet.
The second line in EN localization is
They simply translated it as "devour everything on the the planet" but note that even the localization doesn't imply it can devour the whole planet. The original chinese text will translate to
With its ability to devour anything, it can devour everything into its food but it doesn't say the whole planet in one go.
So I must disagree with the reasoning even though Narwhal 5-B might be possible from Neuvillate chain scaling.