The very act of trying to silence opposition is a kind of confession in itself. Of course there is. I have made it myself. But when you risk injury to your career in the U.S. by defending the interests of the U.S., something is seriously wrong. A proper parallel is not with Joe McCarthy, who at least was trying to uphold America's position, but with the publishing industry in New York during the 1930s, when a book critical of the Soviet Union stood scant chance of seeing print.
Suppression is a good tactic, but a bad strategy.
In the long run, the truth has a way of seeping through. No matter how many clever excuses you make for a Yitzhak Shamir, it's not a terribly good idea to have Americans identifying Israel with Yitzhak Shamir. And it isn't wise, in the long run, to make Americans afraid, in their own country, to speak their minds about a foreign country. They will eventually resent the colossal impudence of it. And the country on whose behalf the suppression was enacted will bear the consequences.