But I'll go further. Suppose we say this is something beyond simulated sexuality. What compelling state interest is there in prohibiting it? Who is being harmed? Why stop consenting adults from engaging in consensual sex acts which harm no one, even if there is money involved?
The horrible things that happen because of prostitution notwithstanding, ALL your questions fully apply to real-life prostitution and the debate of whether it should be legal or not...
It can be argued that illegal prostitution is the worst possible thing for the safety, respectability, financial and economic status, and general well-being of prostitutes. I have yet to see a compelling argument against legal prostitution, especially as it is my strong conviction that making prostitution illegal is *never* a means to eliminate prostitution, once it is illegal it is ignored unless it is specifically required to act against a prostitute. Prostitution is still alive and well, it's not even fought against all that hard. But there's a way to attack someone and dehumanise them, including by the state/law enforcement/system, because they engage in sex work.
It's a tool of oppression and control, not a tool of protection, based on any and all evidence I've seen. It's a "have your cookie and eat it too" approach that allows for the marginalization, vilification, divide-and-conquering of sex workers while still making the profession thrive, catering to the needs of prostitutes' clients (who are rarely punished as harshly OR despised as much as the prostitutes themselves, despite the fact that this attitude makes no sense), *and* forcing many people into sex work, either againts their will or semi-against their will. And while they are harmed this way, they are still seen as the source of the problem by the average Joe, because they engage in a "bad" thing (the fact that they may not actually willingly choose to being usually completely glossed over).
Granted, I brought real life into a comic discussion, but I think it's a pretty interesting point of discussion to come from once you abstract this into robots. The question "who is being harmed?" here is quite obvious because the element of physical stimulation is gone or blurred, as are most of the social and psychological entanglements that are there for humans.
But once you insert those into the mix again, carefully enough, the questions you ask are still relevant. Not as clear-cut, because sex-related stuff does result in harm to people, but I don't think the core of the problem becomes changed in any meaningful way.
And now I done and opened a can of worms... I do wish robot sexuality was more explored in the comic, as silly as this comic is. I think one of the best things about fiction is what it can say about real life. This goes especially for sci-fi.