When the started lining up, OVOs were still available and being sold. I'm sure they have a certain quantity of ovos earmarked for release every day, so they were probably uncertain what was going to happen themselves
option 1: Tell people lining up that they do have them for sale and they blow through their quota selling to VIPs, people riot
option 2: Tell people they don't have them for sale and people leave the line after being in line for ~10 hours. people riot less (probably the best option)
option 3: ¯\_(ツ)_/¯ essentially what they did, no blame can be placed on them