I regret to inform you that your two sentences conflict.
If it is a matter of principle, then potential outcomes shouldn't matter.
And it's not like the US has been a bastion of radical free speech for centuries. The US has frequently restricted speech, starting right off the bat with the Alien and Sedition Acts in 1789; increased restrictions during wartime; strict regulation of obscenity up through the 70s; frequent attacks on NEA funding and hearings on labeling music in the 80s; current right-wingers yanking books from library shelves, and so on.
And that doesn't include private sector censorship such as the Hays Code, the ACMP / CCA, the MPAA, RIAA labels...