I never understood how sex can be a topic for philosophy to make such statements on in the first place.
This is a highly concrete and specialized issue that depends on an individual's concrete values, psychology and physical constitution.
Who is to make statements about what your own concrete and objective values are? What values to look for in another person? How abstract they are to be? And in order to fulfill which actual needs of interaction with them and to what extend?
And knowing that Objectivism enters into this topic, I typically detect certain ideas surrounding and relating to it, that I find rather strange:
Limitation of the need of "physical attraction" to a purely physical pleasure.
No such thing in my opinion. Every physical feature you identify is an aspect of a conscious living being that perceives itself and this world through exactly those physical features of its body, and hence in that very form. And you know this, and only knowing this gives meaning to that attraction. Simple introspection tells you that.
You like a particular form in which he or she exists as a perceptually conscious being (with certain implications even for some of its conceptual values). What you like is a form that physically best facilitates your contact to the reality of another human beings' existence. Of his or her existence as a conscious living entity.
You cannot like "just his or her body", without demanding and knowing that it is the body of a conscious living being that you are liking. And you cannot like "just the aspect of his or her being alive and conscious" without it being so in a particular form that appeals to you. You are seeking some specific conceptual knowledge here, and you want it to manifest itself in a specific perceptual form. That's to a degree of 100% a mental, as well as of 100% a physical need, you cannot separate the two.
Individuals may vary, but how one would exclude that this alone might form to certain individuals an indispensable prerequisite, possibly even a highly important value in and of itself, is incomprehensible to me. Just think of how you prefer watering certain plants only, and like to have certain animals as pets only. Now, how much more exciting is the case of a particular form of a human being?! It already starts with only wanting a particular sex to begin with. Not to talk about all the other physical features, of which there are numerous.
Sex as valid only in romantic love celebrating achievement.
Well, what about things like "puppy love" among human beings? Love driven by infatuation? I can conceive of it as being an immense pleasure and source of mental energy. Certainly enough so, to be valuable. Something to want to keep living on for in order to enjoy. I find the idea of suppressing it repulsive, if not disgusting. Unless you can conceive of something more fulfilling. And assuming of course, the person in question is not harmful.
I think I heard or red Ayn Rand say in some documentary that her sisters were into puppy love, while she was the only hero worshiper. And that she never really understood how that could be enough for them. Whether she outright condemned it, I don't know. But I'd rather doubt that she approved of it, given her demands for "appropriate sex".
The frequent emphasis that your enjoyment needs to be about your achievement.
I find this mind boggling. There can be a million things I could value without having achieved them. Many of them come naturally (like beautiful landscapes I see in nature). Others were built by other people (like the sight of impressive Skylines). I certainly would like to keep them in reality, whether achieved by me or not. In some cases, I might even not want to know in detail how they came about (You certainly wanna eat the steak, but that doesn't mean you wanna meat the cow ).
Identifying the fact that me or other people had to - or didn't have to - achieve those things to put them into this world is not what makes my enjoyment of them possible or impossible. My enjoyment stems from my need to survive, which requires having certain experiences that make it worthwhile. Knowing that "I build this" can be a pleasurable add-on, though.
Achievement is also not the psychological root of the motivation. In order for me to say "oh, there's something I want to achieve", I must first say "oh, there's something I want to enjoy".
All this tells me that values (realized or not) are considered values independent of their achievement, but rather due to the valuing, the prospect of their enjoyment.
But achievement is very often necessary to realize them - whether on my own or on other people's part. Since other people cannot be my slaves and shouldn't, I recognize the need to engage in a certain amount of my own achievement. While recognizing also, that I benefit from the achievements of all the other people as well. Together, we're all better off, plus the free riding. The rest is done by mother nature.
And due to all those achievements, the amount of daily achievement necessary to maintain a desired degree of enjoyment becomes less and less. Nevertheless, you must always maintain some level of achievement, to keep your brain active so you can figure out how to best enjoy. Or to prepare yourself in case some new idea happens to come about some time on what next to realize.
Psychologically, this means that achievement is a means to the end of enjoyment. But it needn't be focused on explicitly. It's simply an implicit part whenever it is required.
I would rather separate the means from the end this way, while still recognizing they're both necessary.