But wouldn't you say something like "hell no" or "no because it's wrong" normally. Saying "no it's not legal" tells me that this is his main reason for not doing it.
Or he was too scared that they would be mad at him if he declined the offer in other words.
Either way, it's a good reason for not liking him. As proven right by all his other actions since then.
Kurono was scared too in the beginning and didn't help Kei when she was about to get raped but at least he changed.
I don't see change in Inaba and frankly I wouldn't buy it if Oku started to change his character now because he wants Reika or because she's in danger. Every hunt is dangerous and his interest in her has been there for a long time. It didn't change him in the past, so there is no reason to do it now.
In fact I don't even think he loves her. He wants her because he thinks that as a designer he fits her better than Kurono. And the fact that she wants Kurono is probably also a reason why Inaba wants her. But I can't see hints in the manga that Inaba has real, genuine feelings for her.
"For Feanor was made the mightiest in all parts of body and mind, in valour, in endurance, in beauty, in understanding, in skill, in strength and subtlety alike, of all the Children of Illuvatar, and a bright flame was in him"