I've always been pretty good at math, so I can't empathize very well with people who are "bad at math". Sure, it's easy to imagine some specific difficulties they might be having, but they could also be having other difficulties which I've never had.

In a sense, calculus isn't "representative of math". But in another sense, it is. If you approach it as a typical student, it requires you to focus on abstract ideas without seeing the payoff, which makes many people uncomfortable.

Now, of course, people who are "good at math" do actually see the payoff. We get bored by pointless things just like everyone else, but math doesn't feel pointless to us, because we feel that it's going somewhere specific. Maybe all the subfields of math could do a better job at explaining the kinds of questions they want to answer, and why.

With that in mind, IMO the perfect kind of math for Scott to study would be basic game theory. He already has a deep understanding of the motivations behind it, why it's important and interesting, and it has almost no prerequisites besides arithmetic. I'd be really curious to see him try. If the intuition behind the Prisoner's Dilemma led him to write the Moloch post, I can't wait to see what he will do with things like imperfect information and mechanism design :-)