Precautions are great. I 100% support any precautions a facility wants to take to prevent tragedies. I don't have any issues with the bracelets or having people working the event wearing particular colors that make them obvious to see. I'd be more interested in whether they have a policy in place in case a kid does go missing. How do they shut the place down? The matching bracelets is pretty practical easy precaution. However, I know the first thing my kid does is take off his arm band when we get inside somewhere.
I agree though, the onus is really on the parent. I've told my child to look for mommies if he gets lost and tell them he doesn't know where is his mommy is. At the age of 5, I feel like this is more age appropriate than finding a station and is a more general rule to remember than the specifics of whatever place we are in. And if he's at an event, it's probably something where other kids would be at, thus other parents. In general, I'd imagine he'd be in much closer proximity to other parents than to safe zones.
Having a policy with how to locate and reunite lost kids and families is super important for the facility though. Perhaps part of that plan would be a safe zone, but it could be something else. Again, this isn't a unique problem to reef shows. Anywhere you go, there will be child predators. Stores, malls, restaurants, etc. I want my kid to be as safe as possible even if places don't have policies in place to deal with the unthinkable. And if they want to implement policies, I'm all for that.