According to the National Underwriters Association business insurance covers rioting.
The police’s objectives are:
Keep people from getting killed or hurt.
Keep the rioting in an open compact area to keep the riot from going into residential neighborhoods.
De-escalate the rioting.
Protection of businesses.
Business protection is way down the list.
I think the Hwy Patrol is doing a good job, from all reports. The are meeting the above objectives.
The insurance may cover it, but the inability/unwillingness of the police to control it may make the future cost of buying that insurance for a business in Ferguson prohibitive.