The Berkeley riots were not about free speech, you're absolutely right. They were waving around the North Vietnam flag and Mao flags to show their support and camaraderie for Marxist movements. They didn't really care about or understand the depth and purpose of free speech as it would be articulated by someone like Tocqueville or such. It was just a political tool for subversion to them. They appropriated it and cheapened it just like they've done with everything else. Like anti-racism. Just look out your window right now and you can see the wonderful results.