I'm not sure they are calling themselves alt-right or match that description. They are also not coordinating attacks but posting their manifestos and celebrating is correct.
I could of course be wrong and I know that the alt-right movement has been mired with white supremacists and others from the start but I did like the description when it at least on surface was not about that but a different take on the dominant version of the right-wing in the US; similar to the tea party movements or difference between socialism and democratic socialism.