He's a poor substitute for Inej in that way. Kaz can't have him the way he would a woman and there's no closing his eyes and pretending. Jesper takes Kaz's answer to also mean he doesn't want to and so he stretches out instead, body long and lean, and then returns his attentions to himself.

"I won't say no if you touch me," he says, gesturing at his own torso.