“Is freedom of speech a biblical value?”
There is no such thing as a right to free speech. Jesus Christ didn’t have one. The apostles certainly didn’t have one. What they had was a divinely authorized responsibility to engage in costly speech. They walked out into the public square with a message almost nobody in positions of authority wanted to hear and inflicted it on the world in spite of all efforts to silence it.
As a result, the Lord Jesus was tortured and crucified. The apostles were delivered over to courts, flogged in the synagogues, dragged before governors and kings and, like Stephen, stoned by their own neighbors and kin.