It is perfectly fair to prevent non-citizens from entering (or staying in) the United States. It is not punishment, it is an attempt at self-protection. Non-citizens are not entitled to an education within the United States, nor are they entitled to visit the United States. When the United States allows these things, it should be considered a privilege, not an entitlement.

However, I agree this is not an appropriate action. Those who believe such actions are going to prevent or stem terrorism also believe criminals will not have access to weapons if guns are banned. They react to situations fearfully, instead of thinking logically. They put pressure upon our government and our government reacts - again, out of fear.