Ah yes, the ageless courtship method of kidnapping a child and threatening to fck him so the man you want will give himself over to you~
(Sorry if that bout of sarcasm was a little too crude -u-)
But yeah I've run into those kinda folks on here occasionally and in certain situations and manga where it's persented in a "sexy" way, it's like . . . I can understand why they're attracted to it and therefore feel the need to defend it but at least in this situation it's not really being presented in a positive light and for that reason I refer the execusion of this rape scene to how they presented the sexual assault from the Duke, where it's being sexualized/romanticized by the victim -.-

Thank you for the amazing translation.
By the way, what the duke did with Jace wasn't dubious consent, it was rape. If your partner say "no", you should stop all sexual interactions untill they say "yes". There was nothing dubious about that, Jace said "no" and begged the Duke to stop. It doesn't matter if he got hard or if he came, if he said no, it was rape. Pure and simple.
What happened with the human trafficker was a little different. He was drugged, so he wasn't of "sound mind", then it was impossible for him to give consent (this is why you shouldn't have sex if someone drank too much. It could be constructed as rape too, since they weren't able to give consent). Even if Jace begged to be fucked, it would still be rape.
Soooo, when Jace thought that he just had gone through that with the duke(the blowjob thing), he was referring to being forced.