> I'd say persecuting political enemies for being "un-American" - or as a recent book declared, "unhuman" - is a very un-American thing to do

Dude. Dude. You've said yourself: this Congress committee went on for almost four decades. And before it, it was Yellow Peril, or anti-Irish sentiments, or manifest destiny with its "the only good Indian is a dead Indian". So, no, it's a very American thing to do, has been since the foundation of the US and arguably from even before than that.