This is either very ignorant or intentionally misleading.
While the script archive is indeed ~25.5 mb large, it contains compiled version of the script which is significantly larger than the raw source. To be exact, the size of actual game script is ~40% of this value:
View attachment 3298691
vs
View attachment 3298692
Out of that 10 mb, roughly half is the code, half is the script. Large parts of the script is copy/pasting of characters placements, expressions etc. Writing-wise, it's also nowhere near an actual novel, so let's not go there.
(but for the record, the mentioned Harry Potter books are ~6.5 mb combined)