I didn't suggest saying this out of the blue!  My recommended riposte borrows the story protagonist's vocabulary and tone.

I understood that much the first time.

  If a woman asks you:

"What you're saying is tantamount to saying that you want to fuck me. So why shouldn't I react with revulsion precisely as though you'd said the latter?"

then, it may be appropriate to discuss, optionally using the word "fuck", why she'd react that way if you'd asked that question, which you didn't, having instead (as in the story) made a much more innocuous suggestion, neither culturally inappropriate nor abrupt and crass.

I think the protagonist makes an excellent point. In fact, she understates it. She mentions plenty of reasons to expect essentially any heterosexual male classmate to be interested in having sex with her if given the chance, so if she's going to be revolted by that, she might as well go ahead and be revolted without waiting for anyone to tell her anything.

The obvious way out of this conundrum, as you pointed out, is to question the premise that she should be revolted by her male peers' sexual desires toward her. This doesn't seem to stop people in general from agreeing with that premise and deeming it self-evident.

As Ilyssa herself argues, how is focusing on the first domino any more innocuous than admitting the hundredth will fall, too? Is there anything to what you call socially appropriate behavior, not abrupt or crass, beyond a lame attempt to deceive her? In fact, since he's probably well aware she won't be fooled, I don't even know which simulacrum level he's trying to operate at; likely 4.

I wish I'd been asked that kind of questions, including the ones in the few following paragraphs, while being both young enough for them to make sense and the situation not to be too disgusting, and mature enough to understand them and know my true answers. At Eric and Ilyssa's age, I'm sure I would have enjoyed and come to crave an unbounded amount of physical intimacy with almost any of my female classmates, provided we got along and could trust each other, but I didn't really know it. I just knew I wanted to get to know them, necessarily slowly, much like I found out, half a decade later, that women tend to emphasize. Funny; in my case, it probably comes from being perpetually isolated and vulnerable. Also, I didn't have the vocabulary to know what "if I offered myself to you" means, so I'd just be puzzled by the question and probably look like a hypocrite to everyone. Also, my parents would have put a stop to that kind of relationship sooner rather than later, and I guess hers would have, too. Also, I was no "one of the more desirable seniors". Okay, I'll shut up.

You're ignoring spousal rape, where a better mate is already only going to be had through the spouse's death or hazardous subterfuge, and resource support for the kids can indeed be expected.

My response is to the Roissy quote specifically, which says, "direct result of actions taken that further your genes' goals" NOT "would have furthered your genes' goals in the ancestral environment." Thus, in the case of forced reproduction, if you were locked in a small room and given just enough food to survive, but then given the opportunity to reproduce with a fertile partner every single time that you were capable of causing conception, you would (I'd hope) not be happy, even though you would produce many, many more times the surviving offspring (if you're male, literally thousands of times the surviving offspring). It seems almost trivially obvious that objectively maximizing inclusive genetic fitness will not make you happy.

The amendment "tend to maximize... in the ancestral environment" changes the equation completely. First, it's very prone to "just-so" stories; one can invent a decent explanation as to why practically any action increases genetic fitness (i.e. celibacy is for aunt/unclehood). Second, because the cause is tremendously indirect, it isn't realistic to say that the cause of someone's increased happiness is the fact that they are (or would be in the AE) more genetically fit, as outlined in the EY post I linked. There's a great deal of truth to it, but it's both indirect and tremendously imprecise. And, more generally, if someone asks "How can I be happier?" the answer is seldom, "Well, think about what would maximize your inclusive genetic fitness in the ancestral environment, and then do that."

On a related note, my problem with a lot of Roissy's reasoning is that he views people in terms of rather binary "objective" Platonic ideals of "male" and "female" and does not account for either innate or learned differences, instead dismissing such as trivial, which is quite problematic, because a great diversity of preferences actually exist.

Edit: Also, wikipedia's phrasing of the sexy son hypothesis contradicts what I've read elsewhere. The idea is that if females generally prefer trait X, then females should choose males with trait X, even if trait X is completely superficial, because then their sons will be more successful with future females. That doesn't make non-superficial trait Y irrelevant, and there is no basis in reason nor a citation claiming it should. The hypothesis is simply an explanation of how an expensive superficial trait can become dominant; it has nothing (explicitly) to do with cuckoldry or anything like that.