I'm an academic. Academics frequently come up with ideas that have, or would have if implemented, abhorrent real-world consequences. If you're a liberal, think hardcore, Heritage Institute supply-side economics. If you're a conservative, think Karl Marx.
It is perfectly legitimate, and healthy, to criticize the ideas which you think are bad. However, the problem is that we as a society don't know a priori which ones really are and aren't bad. People have different opinions. The best way we've figured out to determine which are truly good and bad ideas is to have an open "marketplace of ideas" with free and open debate.
If we criticize and marginalize people who have unpopular (= we think are bad) ideas, then the only ideas left will be the popular ones. And that, I believe, is anathema to progress, far more so than letting bad ideas be aired and eventually lose in the court of public opinion. Another outcome is that the unpopular idea might turn out to be better and win, but would not have have a chance to if it were prematurely stifled. The best way to go, therefore, IMO, is to criticize bad ideas but not the people who hold them.
Humanity has tried before to stifle opposing viewpoints, and largely succeeded. It resulted in the Middle Ages. I prefer an open society.