A portion of them are reliving their glory days in the late 60 's early 70's and their "anti-war", "give peace a chance" days.
Another portion have no grasp of revelancy and project their HATE BUUUUUUUUUUUSH mentality into every aspect of their lives, so this is another straw to grasp at and feed idoitic hope that one of these things will bring him down.
Back in their "glory days", there would be several hundred THOUSAND protesters, not several HUNDRED....
Their "glory" is as pathetic as it is brief....