I'm not sure what point you're trying to make. In science and engineering, being able to provide justification is a core skill. The comparison we should be making is against the human practitioners who are trained in their fields. There will always be a distribution of ability. Saying that there's evidence that people are capable of providing post-hoc rationalization doesn't say anything about the ability of experts to produce well thought out responses (in their respective fields) that don't immediately fall apart under scrutiny.