Until the social situation has calmed down a little bit in America it might be wise to close some of the businesses in Dallas. There is little to gain by staying open for the sake of being stubborn and there is the risk of further violence should the situation be inflamed.
Much of downtown Dallas is a crime scene after the mass shooting of police officers during a Black Lives Matter protest. Law enforcement would have difficult time investigating the crime if there were lots of people around the crime scene. Therefore, it was the right call to close businesses in downtown so that investigators can focus their attention on the crime scene without being disturbed by the public.
Dallas businesses and public areas should be closed until local authorities can be sure the full threat has been dealt with. The suspect in the police shooting indicated that he had placed bombs all over the downtown area and wanted to kill as many people as possible. This statement, coupled with the shooter's actions, should require that the city is shut down until authorities can guarantee public safety.
Given the recent history of the last two years involving racial provocation safety has to take priority over profit. More lives do not need to be lost. While the individual claimed to have placed IED's, the security of the population needs to be foremost on everyone's mind. Too many lives have been sacrificed for those with the intent to do harm. There aren't enough armored vests for whole city populations.