He organized an event without getting a permit.
The permitting process ensures that there's adequate security, traffic control, etc.
He didn't do any of that legally required stuff, and the result was an angry mob. We've been through this. This is why you need a permit for large public gatherings, and why he's legally liable for what happened.
Did they fix the thing where, after combat, my Flaming Sphere runs up to me like a puppy and accidently sets the whole party on fire before I can dismiss it?
::Looks ar patch notes::
Dammit. Maybe next patch