And they know more about his conservatism than you do.
The First Amendment was specifically designed to protect political and religious speech, elements the British colonial authorities suppressed. The Fourteenth Amendment extended the Bill of Rights protections to the states. However, for almost a century after the ratification of the Fourteenth Amendment, state and local governments routinely suppressed pornography. Political and religious speech were never in the same category as commercial or sexually oriented speech. Commercial speech, i.e., advertising, is considerably restricted by law. When was the last time you saw a billboard, a TV commercial, or a newspaper ad for Winston cigarettes? The FDA restricts the claims that may be made for both prescription and nonprescription medicines, as well as for vitamins, minerals, and homeopathic remedies.
The restrictions that Santorum advocates were considered mainstream and almost universal public opinion before the falsified Kinsey Report. Unfortunately, the level of moral depravity in this country is such that Santorum is regarded as an extremist in such matters.