The Twitter messages you're referring to are part of strategic drafted plans by Team ( Al ) Sharpton, Inc.---trying to exert politically charged racial pressure on Florida and the D.A.'s office; so far--none of Sharpton's nasty bag of tricks have worked.
This fool plan of Sharpton's is also NOT working: This isn't Rodney King era 1992 L.A. anymore. Florida's governor and the D.A. both are NOT intimidated by the attempt....and law enforcement there are a LOT more better prepared than 1992 LAPD were.
Since the infamous rioting in 1992 L.A., state and county law enforcement agencies have quietly, for years, undergone intense riot handle training---programs funded heavily by the U.S. government ( under Executive Orders of President G.W. Bush, Jr--who also trained U.S. Army AND Marine troops for the same scenarios).
Even IF Obama holds back sending the Army and Marines ( a fool move to do ), law enforcement has FBI back up--and again: They're ready to handle matters IF racist black rioting goes "flash point".