Actually, you completely agree with me. A Scrum Team very explicitly is self-managing. Agile processes ARE frameworks for coordinating self-management at the team level, and which have been found to work repeatably. That doesn't mean a given one will work everywhere. Specifically, Scrum is probably not ideal for startups doing something truly new, since it assumes there is someone who can prioritize features by their business value.
Why would you tell somebody that they completely agree with you when they just said that they disagreed? That's so rude. You say "That's cowboy programmer bullshit", he says "I completely disagree." Do you really think there's a chance he secretly agrees that his view is "cowboy programmer bullshit"?