The left are absolute masters at redefining words to give them a different meaning than originally intended. Early in 2016, I had an online debate with a lefty on exactly this issue -- "what do you think of the "Alt-right", and my response was "you need to define exactly who you mean by that", which he of course refused to do. He just wanted me to condemn them without having to say exactly who I was condemning.
I think the original meaning of the term described a somewhat more populist, more confrontational group of conservatives who wanted to fight against political correctness, and what they perceived as the "go along/get along" mindset of establishment Republicans. The left attempted to redefine the term to include "white supremacist/anti-gay/racist". People who previously (and proudly) identified themselves as "Alt-right" but weren't racists objected to it, and that's pretty much been where the battle lines are drawn. I think some establishment Republicans have pushed that same definition because the "Alt-right", however described, threatened their control of the GOP. And of course, I'm sure there are some self-described "alt-right" types who are racist. But certainly not all of them.
I personally never liked the term precisely because it wasn't well defined, and therefore could be characterized as almost anything by either supporters or detractors. In any case, I think any finger-pointing or condemnation/criticism of the "Alt-right" must necessarily be preceded by agreement on exactly what the term means. Otherwise, it's all kind of pointless.