Can I just focus in on the last bit (if that doesnt work we can go back to all of it) because I think that might be the core of the kind of disconnect that's happening?

You quoted this bit:

We need to be able to admit that what perpetrators do is what the world calls sex, and that it is not nice, and that it is not the fault of survivors and its other casualties for not finding it nice but is in fact due to the nature of sex under patriarchy.

And said:

... when you said that sex is not nice, no matter who partakes in it, that's when I felt like I was being preached to...

Lemme reformat the bit of the essay you quoted and see if it changes its meaning?

We need to be able to admit that what perpetrators do is not nice (even though the rest of the world routinely calls that same thing "sex" - like, "what's your problem? you had sex then regretted it?"), and that it is not the fault of survivors and its other casualties for not finding it nice but is in fact due to the nature of sex under patriarchy.

That way it sounds a bit like a tautology, sure: "when people do bad things the bad things they do are not nice". But it sounds like a tautology, I think, because I'm trying to uncover a true thing.

An observer who has looked at sex which both participants may well have found nice, and who also looks at what a perpetrator does, might well struggle to articulate what is different in the perpetrator's behaviour.

I'm suggesting this isn't because the observer is confused or wrong but because the social scripts for sex and the social processes of perpetrating assault are deeply interwoven.

That's why perpetrators can say, "Wtf? I was just doing what anyone does and she's gone and screamed rape!" and they're not necessarily lying. That's why studies which look at the attitudes of perpetrators tend to find that they're pretty normal people without any especially weird attitudes about sex. They're doing broadly normal stuff and there is something messed up about normal stuff.