Arguing your opponent’s views can help you acquaint yourself with and demonstrate (good will) you understand their arguments.
Why should people use this category? What is it for?
People speak too often and too freely. This would give them something to think about, to confront. This sort of activity also results in more convincing arguments–when you understand your opponent, you understand their weak points, how to counter them.
How exactly is this different than the other categories we already have?
What should topics in this category generally contain?
People should be challenged to argue their adversaries’ strongest points, the points they fear the most.
Do we need this category? Can we merge with another category, or subcategory?
Seeing as how the mission of the Infowars Army is Activism, I recommend whittling the site down to discussions that lead to Activism (News, Activism, Site Feedback), but if you’re intent on having other categories I would think the category could be a valuable tool in users’ self-reflection and self-development.
You may say that the category would be superfluous due to the quality of the people on the site–I say it may be true for some or most but that it would also provide users with opportunities to improve themselves.