He doesn't want to fully go into the details. It feels like something between Tidus and him, after all. But it's not as if Inigo can't tell Senku anything at all, especially since there was a part of that which he does feel like he can share openly. If not just because it's logical.

"He was worried about me," Inigo explains. "He almost told me to just not do it at all. I managed to convince him this time, but I don't know if I could do it a second time. And I also just don't want him to have to feel bad because of worrying about me in the first place."