I can't think of any law which prevents you from repeating a presumably impromptu question that someone says publicly. It occurs to me that a person at an academic conference might argue that their strung together words are really cutting edge and therefore not to be repeated by anyone but themself, but then they shouldn't have spoken them in public. On the one hand, the very point of academic conferences is to share ideas. On the other, maybe people sharing ideas assume they are only sharing with fellow attendees, not with the entire internet!
I think the problem is not a legal one, but a professional and interpersonal one. In other words, etiquette. Meaning that someone who does this won't end up in court, but might end up being mistrusted and disinvited from future events. Inasmuch as that's the case, proper etiquette will be dictated by those who travel in the social circle.