[flagged]
It's very obvious if you think about it. If the encoding on the memory is n that doesn't mean it represents "n" data conceptually. It can be n+x for any value of x. For example, you can declare 0 represents $0, 1 represents $0.01, 2 represents $0.02 and so n represents n cents. This is pretty common in tax calculation applications. Then, you can also say n represents n+99^99 so that what GP said holds. They just provided a formal argument for it which proves it by induction, as we call it.
This is contradiction, I think.
Assume n (exists and) is the largest number representable in 64 bits is statement 1.
The numbers in the n+x system are larger than n is statement 2.
That causes a contradiction and since statement 2 is true, statement 1 must be false. The addition in n+x is not induction, just a way to define a system.
The encodings in this article are self-extracting archives; although they don't use a bloated, arbitrary format like e.g. x86_64 Linux ELF executables. Instead they use Binary Lambda Calculus, which has a variety of interpreters (the smallest being 206 bits, written in BLC itself)