Nonsense. Focusing on people who are different isn't a trait exclusive to Americans. Every group of people throughout history has shared it--even those without any discernable difference to an outside observer. Norwegians dislike the Swedes. Hutus hate the Tutsis.
From an American's standpoint, native Greeks and Italians are different, but we're not focusing on them. We should focus on those who ethnically and religiously fit the profile of those who have perpetrated 99% of terrorist acts against the West over the past 25 years. Timothy McVeigh is an anomaly. You lose credibility when using anomalies to prove a point.