Though in no way condoning what the police did, I wonder if he had a record and was under surveillance for drug trafficking. The cops used a rolling stop sign violation as an excuse to search him. But obviously they went way too far in their actions.
Yeap, wonder what got him on their radar. He was probably a bit upset about being pulled over for rolling a stop sign at Walmart in a town like Lordsburg... and those officers showed him...
The rolling stop sign violation is engineered for the purpose of providing probable cause, as are many traffic laws. The public thinks they are being protected, the LE establishment just snickers at them and uses the law for what it was intended: Subverting the 4th amendment.