In situations like this, the answer isn’t to argue over the interpretation of the words: it’s to fix the words.
If the writers intended “no excessive capitalization or excessive grammatical errors”, then it should be changed to that.
If the writers intended “no excessive capitalization and no grammatical errors”, then it should be changed to that.
Both situations remove the ambiguity and prevent pedantic internet arguments about language interpretation.
I wouldn’t be surprised if all shells have some form of that, but not enabled by default. I know Bash does, but I’ve never turned it on.