Please read up on why/how the FCC was established. Just because the FCC rules something doesn't mean it is Constitutional, however. Their rulings can and are challenged in court and that can be said of laws made by Congress (like the recent example of the health care law). AFAIK, the only rules/regulations that can't be overturned by the Supreme Court are those rules/laws/etc passed via Constitutional Amendment.
The Supreme Court
ruled that expression/speech may be subject to certain
criteria to see if it qualifies for protection under the First Amendment.