The crowd who managed to silence a speaker last week accomplished something, to be sure. But it wasn't a blow against racism, fascism or police oppression. It was a step towards a closed campus where mob rule determines who can speak and who will be shouted down.
Protesting is important in that it's the option to turn to when critical discourse is stifled. But protesting the opportunity to hear and engage critically with an ideology is damaging for both parties involved.