I think it depends entirely on your confidence in your own ability to think on your feet. Me? I'd turn it down in the absolute certainty of being rendered an idiot: I can't think on my feet, I'm slow to formulate my thoughts, and ten times slower when someone needles me or pings my privilege/condescension radar.

On the other hand, if you're good at that, it might be awesome to take the guy down a peg in a public forum!