Actually, if I am reading Simon right this suggests that there is no need
to cover ABNF in the code requirements.
If the human being has to write the code that has the same meaning, then
the copyright on the ABNF is irrelevant to that code segment. This
argues that ABNF should be considered text, not code. It does not argue
that there is an error in the suggested definition of code. Copyright
does not protect the idea of the ABNF, only the expression.
Remember that the point of allowing code to be modified is that you need
to include the code in the program, and you may have to modify the code
to make it work.