As a principal point of view, your interviewer will look at cases in the way he prefers to do so. If he is interested in the audit side, you absolutely need to adapt to his requirement.
Same for a real-life project - it's not what you are interested in, it's about the scope of the engagement and the clients needs.
However, that being said, for the interview situation I absolutely recommend to clarify the scope and goal immediately at the beginning of your case. If your interviewer somewhat still insists on the audit side, it's perfectly ok to clarify (once more and finally) if all other perspectives can disregarded for your discussion.
Hope that helps - if so, please be so kind to give it a thumbs-up now with the green upvote button below!