I see a few distinctions between code and prose.

Code is written with two kinds of readers in mind: the computer and other humans. Prose is written just for humans.

With code, there is a very precise set of rules determining whether the code will be readable by a computer. There is no correspondingly precise set of rules for understandability by humans.

I can see the analogy between PEP 8 and grammar rules, but I think there's an important distinction in the provenance of those rules. PEP 8 is a formal proposal adopted by the BDFL. There is no mechanism for submitting or approving formal proposals for English grammar rules. So the spoken language is always the authority on what's correct and what isn't.