The flag (no capitalization required) is a piece of cloth.  The symbol of the American patriot is the freedoms and ideals on which this democratic experiment was founded.  Freedom of protest is one of them

Worshipping a piece of cloth at the expense of the Constitution, as you are doing is as crazy as worshiping a Christmas tree.  

And these men have a legitimate grievance.  Just because you're not a victim of institutional and systematic oppression and bigotry doesn't mean their struggle is less real.