Did they fight so that citizens would be allowed to say only what THEY thought was acceptable?
I don't think so.
It's not THEIR responsiblity to filter out the garbage. It's not the LAW'S job to remove these vermin from our midst. It's OUR job to shun them, to shut them out even if we don't shut them up.
THAT is freedom. And THAT is what they fought for.
The Constitution also does not prevent the government from directing ridicule and contempt at the contemptible left; nor does it preclude legislators from inquiring whether public funds are being used simply for left-wing propaganda exercises at public institutions, and holding those who do so up to public ridicule.
You seem to have a rather exaggerated sense of how much of an internal 5th column a country can have while still being capable of defending itself.