The things Donald Trump says (such as "stop Mexicans from coming into our country illegally" or "ban Muslims from immigrating to our country until we're confident in our terrorist screening process") offend a LOT of people. People who don't believe such things should be said, or even talked about. People who, when someone says these things, viciously attack them, saying they are morally wrong for thinking those thing…
This is just the Tolerance Paradox. https://en.wikipedia.org/wiki/Paradox_of_tolerance Except not really. There's no movement on the left to outlaw what trump is saying. Pointing out something is racist on twitter is not "squashing dissent".
[1] http://tech.slashdot.org/story/16/01/30/1847207/why-does-twi... [2] http://thevine.com.au/politics/australians-want-ban-donald-t... [3] http://www.breitbart.com/tech/2016/02/08/twitters-attempt-to...