I acknowledge it's being racist, but if it's to ensure that hundreds or even thousands of people survive, is it too great a price to pay?
Unfortunately it's a fine line between being racist and using objective screening. For example, a cop is told that a man with black (not light brown) skin committed a crime. Is the cop going to screen everyone he sees (no matter what the skin color is) in order to not come across as racist, or will he narrow in on a man with black skin to save time? Now, when you are trying to prevent a crime, it's a bit harder to do that since a criminal/terrorist can be of any background or color (not the variety in the UK bombing). While I don't think it's wrong to give someone of Middle Eastern decent a closer look, you have to look out for anyone that seems to be acting unusual.