Just want to start off by saying that I think the KKK and any white supremacist groups are fucking morons and I'm glad that there were so many counter-protesters there to show those losers how out numbered they are.

That being said, you are right there is nothing in the constitution specifically about the right to protest. However I just found this on Wikipedia..

The right to protest is a human right arising out of a number of recognized human rights. While no human rights instrument or national constitution grants the absolute right to protest, such a right to protest may be a manifestation of the right to freedom of assembly, the right to freedom of association, and the right to freedom of speech.

If we deny these assholes the right to protest who's to say that we couldn't be denied the right when it comes to something like the bullshit abortion laws the right has been pushing here lately.

Once again I hate that it could even be implied I'm sticking up for these assholes but I do believe that the right to protest is a very important thing for democracy.