Yep, there is nothing wrong with criticizing the US govt. But pure criticism, with no solution other than saying our govt should become socialist is not criticism, it's sedition against the best govt this planet has yet produced.
If they tried suggesting improvements, instead of tearing the govt down to rubble and rebuilding it as a socialist disaster, I suspect conservatives would have absolutely no problem with their speech. Disagree with them? Yes. But I speculate they would support their right to free speech, because nothing is more American than that.