If you use social and economic pressure to silence someone you are practicing censorship. I am not sure where the left got the idea that only governments are guilty of censorship. Stopping someone from speaking in a public forum is the moral equivalent of book burning. Idea is the same, stop the spread of ideas you don't like.
It is easier to fight stupidity like this in open then it is to fight the slippery slope of letting a vocal minority censor what we can see and hear and which ideas we are allowed to be exposed to.
The best solution would be to allow people to sue anyone in court who organizes a boycott to have them censored. Of course all the little snowflakes clogging up our universities would melt and some of the schools might even have to start teaching things of value. I mean what is the point of getting a degree in female studies if you have to hear white men who don't agree actually speak?