I am worried that for someone who might not hold very strong beliefs, you may have to ask them to engage anti-natalism or nihilism or some such really strong memeplex. I do wonder if someone who has not done this kind of thing before, may stare too long at the abyss and break.
One safeguard against this would be doing it with more advanced students instead of freshmen, as I suggested elsewhere on the thread, so that they are already somewhat used to evaluating arguments and claims in a detached, academic way. Another one would be pairing opposite views: white nationalism and black liberation theology, extreme radical feminism and conservative Catholic theology, etc. Then people with weak preexisting convictions are unlikely to be swayed to one side.
From Julian Sanchez, a brilliant idea unlikely to be implemented: