Not on purpose, and they didn't keep or memorize it.

The GP comment says "After I shopped a few other companies to see how our plans compared". That sounds pretty "on purpose" to me.

What does "keep or memorize" have to do with anything? They intentionally abused a misconfiguration to view private information.

I think it's reasonable to disagree about the ethics of that, but I don't think it's really debatable that it was intentional.

They were intentionally viewing plan information. The personal information wasn't the goal and wasn't retained.

"private" information is too vague of a term.