They cannot bare the fact that they have lost the argument.
This is why they want to shutdown anyone that talks some sense.
But what does this have to do with the alt-right? You've got people like Richard Spencer *****ing about how his free speech is being compromised while he calls for the 'peaceful' ethnic cleansing of black people. Sorry but no matter how many 'peaceful's you attach to that it's still an inherently intolerant & violent process - and free speech does not cover hate speech. I love how people in the 'alt-right' hark back to the good ol' glory days of their grandparents when society was more conservative & white than it is now and people
shot Nazis but now it's all 'oh, we're not being tolerated for our racist & oppressive views and I find that offensive'. Sorry, but if you're calling for the removal of an entire ethnic group from society or if you hold politics sympathetic to this position then a few punches is the absolute least of what's due to you. I don't condemn the rioters in any way. They should not have to sit back and pretend the prattlings of yet another white supremacist should be allowed to pass unchallenged.
Neo-nazi & other white nationalist views need to be kept on the fringes where they belong and can do as little damage as possible. Irrational, intolerant politics like the 'alt-right' deserve only an intolerant response and I've lost too much patience with Western politics to be able to pretend otherwise any more. It's because of people like Milo and Spencer being allowed into the mainstream that minorities are going to face the biggest attacks on the rights they've fought for decades to gain - after people on the right have spent
years whining like spoiled little brats because they've had the legal option to discriminate taken away from them and they can't face another day not being able to deprive other people of their rights.
EDIT: This isn't just true in America, it's true elsewhere. It's because of groups like Britain First that a British MP was
murdered for her political views during the run up to our referendum on EU membership - her killer is in a picture posing with a Britain First banner. And back to America, now Trump has removed white nationalist - sorry, 'alt-right' groups - from the Counter Violent Extremism program despite the fact white supremacist and other far-right 'patriot' groups are responsible for
waaaay more terrorist attacks on American soil than Islamic groups.