Because for a random passerby you can have them withness and be responsible for the withness statement. Clearview can fill their database with crap, or even fake some data, to manipulate the police investigation. Because Clearview knows this is not only possible, but also likely, the database matches their should not be used as any evidence. If such tools are used, a lot of innocent people are arrested and just arresting you for a murder, even not guilty, will destroy your life.