Joseph:
Blocking streets, even without spitting, is an act of aggression against the public. It is totally unacceptable, and should be judged as such by anyone with a smidgen of morals. The right to demonstrate exists, but it cannot involve the crime of being a public nuisance or causing damage to others.
By the way, those getting arrested are probably draft dodgers themselves, and there should be an effort to increase the number of arrestees from 2 to whatever.