Are you suggesting he just prance around the Yuuki residence and the police and proclaim Sugou a bad guy. He wouldn't be taken seriously. This also applies in the real world. Lets say a powerful politician is embellishing funds and a lowly wage worker happened to know about it. Even if he confesses to the media it will only make a big deal for a few days and then be forgotten. Then said wage worker disappears never to be seen again...
Oh and about the finding Asunas hospital thing: