Look, as a kid I watched stuff like South Park, Beavis and Butthead, Drawn Together and other edgy stuff because at the end of the day kids always want to feel like grow ups by watching things they are not supposed to watch, but the difference is that I knew my mom would ban my ass from the tv for watching that stuff which added a sense of danger to what I was doing and made it more fun, not take me to a South Park QnA panel, so that's just bad parenting outside of the control of HB crew. But even if, I bet you Trey and Matt would have handed this situation way better than these dunderheads.
I don't see why they couldn't just reject to answer any question from the kid out of sheer principle, It would have come out as rude but you need to set the example, specially not make the situation worse by then prociding to make inappropriate comments. Very bad look, all of them came out as being scared of putting limits on their own fanbase which reputation is alredy in the gutter and situations like this keep worsening it.