I don't think you understand the threat profile of a large public event. The typical threat to events like this are idiots who mimic crap they see on YouTube. Public safety isn't an exercise in evaluating every theoretical threat, because that list is too long to address with limited resources. It is an exercise in evaluating which threats are most commonly to be exploited, and the easiest to protect against. This is how you most effectively protect an event with limited resources. It is different than the theoretical threat evaluation that someone doing computer science might think about.