While I do agree that Rose seeking out sex with anyone other than the duke, and possibly Leto, at this stage is premature, a key element that needs to be focused on is why she's doing it. She didn't fool around with the pirates because she wanted to, she fooled around with them because she thought she had to do it. Rose is accustomed to getting what she wants and what she wants is Leto to be safe, happy, and successful. Update 13 focuses on the first one, she wants him to be safe and she's not thinking clearly because her mind and body is being twisted by the pleasure provided by the duke. She's been shown that sex is not only a powerful weapon but also the only weapon she has. So she uses it against the duke first and when it seemingly works for her she realizes that she can use her body to get things she wants and in her twisted state of mind she did just that with those two pirates even if she didn't actually fuck them. Rose is a captive engaged in sexual relations with her captor for the sake of her people and the man she loves, and she will continue to fall further and further into corruption. The path to hell is paved with good intentions.