So he is attacking Bezos wife and not the facts she wrote? https://yourlogicalfallacyis.com/ad-hominem

I don't think it's a logical fallacy: he's making a general point that the wife of his subject is not going to be particularly impartial.

When accused of getting the facts wrong, this journalist responded by attacking the impartiality of the accuser. A person who didn't know the meaning of the word "fact" might find that insightful.

Credibility of the witness (bias) is always a proper issue for argument.

Well, you would say that, wouldn't you?

If you'd read the article you'd note that he barely addresses her or her status, and primarily responds to her review and elucidates his reporting process.

I quoted that line because I think it usefully reframes the conversation. Journalists certainly can be biased, but the good ones try very hard not to be. Spouses by definition are biased.

Stone's comment is rather dumb. Insofar as Mackenzie was accusing him of "bias" (not a word she used) she might be interpreted as accusing him of trying to tart up his story to make it exciting. She appeared to be more concerned with Stone getting facts wrong and pretending to understand what Bezos might have been thinking.

Stone's comment was defensively knocking over a strawman and I wonder if it is indicative of his overall seriousness as a writer.