"grammar of assumptions" loses me a bit. I would need a more elegant explanation of what they are trying to say.
But the first couple lines about language, that our grammar goes unspoken, can be both right and wrong. Not sure what they are talking about exactly. I am curious, there is a citation there "5". What is it citing?
It was used as an insult/out of anger, so both homophobic and sex-negative. I'd say it's an indicator of serious sexual dysfunction - the sort that should be addressed in a professional setting.
Grammar going unspoken is that it's assumed: we don't speak our grammar. Grammar being assumed means that we assume the grammatical constructs for the language (loosely used here as it also covers film, political acts, etc) which structure it, hiding that the way we speak is due to a structure. This is the same way political grammar operates: we live our lives in such a way because there is a societal structure that dictates that, though we don't acknowledge it.
The citation is Benveniste, Problems in General Linguistics
Like if what they mean by "unspoken grammar" is that we have this organic structure inside us in some way, then yeah. But is it "unspoken"? I am not sure if I can say that, as our awareness of it is from spoken language. The details of it are learned from spoken language. I may not be explicitly expressing the details as I use language, but those details are evident from my speech. So is it really unspoken? I don't know. So yeah I want to see the citation to understand what they are really referring to.
It is one where you make explicit in the way you speak why your sentence is structured in that way, one where you acknowledge that it only makes sense within that grammar.