The reason I said suspiciously is that it seems to me that he is trying to protect Konohagakure and its shinobi for unknown reasons it was very much like when Itachi Uchiha visited Konohagakure as a member of Akatsuki. But I could well be wrong. We saw Katasuke and others observing Kawaki’s body.
And Katasuke immediately said that his passed out because of overheating. He also added that Kawaki’s body is modified, that is he is a modified human being. Kawaki isn’t a synthetic human but a real human whose blood vessels and other internal organs seem to be modified with the help of technology. Mitsuki was keen on knowing more about Kawaki as he himself is a synthetic human.