You did a good job with your business audience and explaining specifically why would this incidence affect them. On the other hand, I think your pubic audience needs a little further attention. You mentioned what has incidence has made the public audience see, however, this does not necessary constitute a clear relationship with the question: why would the public policy advocate audience be interested in this topic?
Before answering this, think about your audience itself, just for a moment. What kind of an audience is a public policy advocate audience? Who are them? What do they do? What are their main concerns? Ill give you one example to get you started. One of their main concerns could be public safety. How is the attack in France effect their thoughts on US public safety? What can they learn from this attack? What happened was incredibly sad, but is there anything that we can learn from the incident so that we can protect our own people in the US? You can think of other forms of terrorist attacks as well: a terrorist can use anything, from a truck at full speed, to old fashioned guns and ammunitions, what is the most relevant form in the US?
These questions might not all be related to this particular discussion post, however, i believe they will give you a clearer direction once you think you can answer the majority of them.
I hope this hope. For the rest of the class: please remember you are welcome to reply to any of the questions posted here, I want to see interactions among all of you: what do you think about this topic?