A term you use to describe an non existent group of violent people when you're a racist but also POTUS the alt-right did commit a crime against humanity and you need to find a BS excuse not to condemn the nazis actions.
There were violence on many sides. What about the 'alt-left' that came charging at the, as you say, the 'alt-right'?
"Alt" is German for "old". Alt-left is Old Left, in the form it existed before 1990. Alt-left supporters do not want identity politics, SJW or other modern stupidity. Alt-left supporters want Communist revolutions and Five-year Plans, they remember that class struggle is about class as it exists in political economy, not some kind of "gender" and other imaginary constructs.