It would actually limit police to just focusing on those that fit one racial profile . But what if the next bomber happened to not look Arab? What if the police got so focused they missed other forms of terror. Timothy McFay was not Muslim. There are KKK ,Neo Nazi ,and other groups out there also just ready to commit acts of Terrorism.
If we start rounding up everyone who looks Muslim police forces are going to be quickly over loaded and other crooks will take advantage of that. The human Coach Roaches will have a field day when the light no longer shines their way.
Trump just doesn't get how limited the police forces in this country are ,what are we going to do institute martial law bring in the national guard if so then we become a police state and we can kiss our freedom goodbye and the Terrorists get what they want and win