I am an avid support of free thought and speech as well as peaceful protests, but I would have cracked somebody upside the head and beat them into silence if I was there.
I understand and acknowledge the contradiction.
There is no contradiction.
They are free to say anything they want. They are not absolved of responsibility for the consequences.
The "speakers" and anyone else you so desire (their employers, their sponsors, their parents, anyone who does buiness with them, etc.)can be ostracisized from society. The rest of us are not denied freedom of action - only the government cannot take action against them for their speach.
And you could always take the risk and beat them to a pulp. You could take the chance that one person on your jury would see this speach as "inciting a riot" and refuse to find you guilty.
A rational person would understand that the speakers are responsible for what they said, and one consequence was they got beat up. I would not convict. A beating would be understandable and rational outcome of their actions.
Freedom of speach and freedom of assembly are not freedom from responsibility.