Most of the outrage contests I see have little to do with substantive arguments, so I don't know how much those would be helped by getting people to engage seriously with offensive ideas. Honestly I mostly see folks refuse to engage with arguments from the opposing tribe at all, or they pattern-match good or new arguments to bad, familiar ones and ignore them.

It's still a cool idea, and if I had the time and initiative to run an online rationality-related course, say, on University of Reddit, it would look something like that. It's definitely important (as he points out) to find bad arguments from every camp, and I would probably assign weak arguments for tame mainstream beliefs, too.