Answer these questions: how can someone or something "command" extremists when they're "extremists" out of norm (can you command a crazy man?)? have you ever wondered why Taliban aren't allowed in All Arabian Gulf countries, Egypt, etc...?
Finally, to the bolded part, in the first sentence you're saying that Islam supports violence while in the other you've said that Islam isn't particularly violent. So, which one is it is Islam violent or not? isn't it just extremists that are violent?