Of course as long as they do not block traffic, speakers or otherwise be disruptive. 

Unite The Right had every right to rally too-as long as they do not block traffic, speakers or otherwise be disruptive. 

The KKK also has every right to rally , as long as they do not block traffic, speakers or otherwise be disruptive. 

Antifa also has every right to protest, as long as they do not block traffic, speakers or otherwise be disruptive. 

BLM also does, as long as they do not block traffic, speakers or otherwise be disruptive.

*The driver had no right to even drive towards a group-much less run them down and kill someone. 
*The  shooter in Dallas had no right to open fire on a parade. much less kill people.