That's certainly something to consider as a concern. I'm still not really digging the design concept in general though.
The one example to your point that comes to mind would be the Kansas City Convention Center where an interstate runs underneath it. I've been in the main hall before with 20,000 people and its something that even caught my attention 15-20 years in a post-9/11 world when that was really fresh on everyone's minds. It doesn't seem like a problem that is easy to fix or address, so maybe the solution right now is to ignore it as a risk and hope for the best?