To the extent that Newcomb's Problem is 'about how you view free will' people who two box on Newcomb's Problem are confused about free will.

I don't think that's fair (though I also don't think Newcomb's problem has anything to do with free will either). The question is whether one-boxing or two-boxing is rational. It's not fair to respond simply with 'One-boxing is rational because you get more money', because two-boxers know one-boxing yields more money. They still say it's irrational. It would be question begging to try to dismiss this view because rationality is just whatever gets you more money, since that's exactly what the argument is about.