That he doesn't done what yet?
I personally wouldn't recommend doing this unless you are facing 24/7 persecution (I am not a sovereign citizen nor do I see any reason to become one in the future), but it is a movement which shouldn't be handwoven away (moonbat liberal groups like the Southern Poverty Law Center hate the sovereign citizen movement, which should lend it automatic legitimacy). When the illegitimate squatter in the White House explicitly allies himself with the teenage thug, what reaction would you have? When you consider that Hussein Soetoro is not satisfied with the ruling and is doubtlessly trying to have a government agency extort or kidnap Zimmerman, could you blame Zimmerman for becoming a sovereign citizen?
George Zimmerman refuses to become a sovereign citizen because he is optimistic for America's future. He selflessly gave his life for the protection of his community, and continues to be a model citizen.