We weren't there, and the article is light on details, so we can only speculate. I see two options here:

a) The potential employer vastly overstepped commonly accepted boundaries.

b) It was totally implied that the questions were to be answered in the context of work. "What was the hardest challenge you had to overcome?" in that context relates to e.g. debugging a hard concurrency problem, not your divorce.

What stood out to me is that whatever interpretation is the correct one, the candidate was willing to give (apparently) deeply personal answers. That's just something to adjust for in upcoming interviews, we live and learn.