TBF, I do not really think that the Demon World being infinitely larger than the Human World really matters, ultimately (in this Wiki that is).
The reason is because by the virtue of them being both 4-D SpaceTime continuums, they're by default Infinite-Sized, otherwise they'd not be Universal+ to begin with, the 3-D size of a universe ultimately matters little in its tiering, as the 4-D axis of time is what matters and makes them Uni+ in AP after all.
This still wouldn't make the Demon World even 2-C tbh. The blog you linked seems to only confirm that only Human and Demon Worlds have different time, but the "universes" inside the Demon World would still be part of the same space-time continuum, as:
Nothing says that the universe made by Mundus is its own space-time continuum, just another place in the same timeline at best.
Not to mention that being infinitely sized compared to a single timeline is meaningless regardless, as what would matter here is the distance between universes as that stuff is 5-D (as it's between 2 separate 4-D stuffs), something the Demon World does not cover, as the requirement for 2-C to 2-A is to affect also said 5-D distance instead of just 4-D things.