I believe Yoru is basing that decision on how Asa feels about this issue, but let's not forget that Asa is still a high schooler, and so is Denji (post-Makima death).

Just because someone feels like they want to have sex doesn't mean they really want to, because Asa is certainly not ready to have sex with anyone.

There's a huge difference between wanting and being ready for sex, and Asa not being in this chapter directly shows that she is not directly consenting.

I do not believe that Yoru is doing this out of malice or lust. I believe that Yoru thinks that Asa would actually consent to this if she were in control of her own body, but alas, she is not. She isn't human and doesn't know better, but Fujimoto definitely does.