I'm having a hypothetical conversation about 9/11
Why would you talk about 9/11?
Everyone has an opinion about 9/11, including me.
If you find it that interesting, then I say talk away!  People should feel free to talk about the things they find important or interesting.  That's how good conversations happen!
I agree with you there, people shouldn't be scared to share an opinion.
Being open with people is the way to go. This could lead to really intuitive conversations.