[panarky]

I agree that ad hominem attacks are generally counterproductive when your goal is to evaluate an argument.

However, when deciding whether to invest hours reading and discussing his latest arguments, the author's credibility is a factor.

[wyas]

Preston has some beliefs that don't make a lot of sense, I agree. But his ability to reason about technical facts is not impeded.

There is no fundamental argument he makes that can be refuted soundly, besides just disagreements in opinion.