Loved the article and summary of James' position. I haven't read James so perhaps this is misfounded. Nonetheless, one thing I noticed is that this, James' rebuttal of determinism, is based on a moral category, regret. And so his rebuttal stays in the realm of morality, indeed of choice.

It doesn't actually touch the ontological status of determinism. He basically states that because determinism requires us to accept everything, we should let go of regret. This leaves determinism untouched, and he argues for free will as a moral imperative.