The last thing Shanks had wanted to do was burden Uta with information that could have put her at risk, and it was just difficult for Shanks to talk about his past, much. It wasn't something he said much of by habit, at this point.

He doesn't just listen to Uta, he watches her body language, notes that she shakes her head, but still coaxes, "After what?"

If it helps her - none of them have been through that, yet, so they don't know what happens with her, and neither does Shanks. Of course, he wants to know everything she's been through and hear everything she wants to talk about.

If Shanks had any idea what she was thinking of in regards to sex, he would point out it doesn't have to be casual if she doesn't want that. She go for whatever she wants.