The interest of the task force has nothing to do with actually categorizing anyone the project takes an interest in and it isn't definitional. The project doesn't make classifications and the article isn't included in any categories reflecting serial killers, mass murderers or spree killers, nor does the page use infoboxes used for such persons. In fact, the interest is mainly based from the "related topics", which includes persons considered "outlaws". Any wikiproject can express an interest in an article for a variety of reasons and is in no way considered definitional in relationship to the project name. It's kind of like saying Billy the Kid wasn't a firearm either, but that project takes an interest in the article.