You highlight the work aspect of sex work as if I’m saying it’s not work, or to say that it‘s work only quantitatively different from manufacturing goods, delivering goods, etc. I’m not saying sex work is immoral or impure or condemning it based on moral judgement.

Ok, maybe I was wrong about what you were saying. Do you think sex work is work, then?

Someone may sleep with many members of society and be supported in their needs by the community through the immense wealth of the people under communism, but the support of their needs would not be predicated on their sleeping with members of the community.

Would the needs of any other members of that society be predicated on the work they do?

And their activity would necessarily not contribute to the welfare of the whole community but only persons selected.

I'm not sure what you mean by this. Surely making sure the members of a community are able to lead happy and fulfilling lives is contributing to the welfare of the whole community. Human sexuality is undeniably an important aspect (for the majority of people) of a person's over all sense of happiness and fulfillment. There being members of the community that help ensure everyone else in the community has that sense of fulfillment, members of the community who are explicitly willing and happy to provide it as a service (labor), is a positive, even necessary contribution to community wellbeing.

Replacing cash with goods doesn’t make prostitution not sex work or change the relations at play.

I never implied otherwise. I wasn't the person who said "some people will always be willing to exchange goods or labour for sex regardless of economic or political system." But they are correct, and you are not when you call that "bourgeois philosophy" and "utter nonsense." Even in a system where that kind of tit-for-tat exchange is unnecessary, it is absurd to say that it will never happen.

People misunderstand communism, due to a misunderstanding of its relation to early communal society, as some sort of return to the end stage of historical communities where everyone lives in common low development and individual exchange happens under the table.

That may be, but that is not an error I'm making. As I briefly mentioned in a response to another comment, there will always be people who are unable or unwilling to form the kind of relationships usually required for sexual activity and thus sexual fulfillment. There will also always be people who choose to develop skills that help provide people with that kind of fulfillment sans any other form of relationship. You may say that such a thing is so different from the kind of purely transactional relationship we traditionally characterize as prostitution that it may as well not be called prostitution. Fine. But the same thing can be said for countless other forms of labor that people do under capitalism to survive, but that under communism would just be "something I enjoy doing," that is still labor and provides a service to society. Like an actor who enjoys giving performances that provide other people with entertainment (as one of countless other possible examples).