I'm going to continue operating under the assumption that Author intended his advice to apply to traditional hackathons, since that's the language he used.

> I think he means take some short cuts if time is short to show your business logic.

Even if that is the case, covering up the fact that you took a shortcut is still cheating. It's fine if, during your demo, you say something like "this is a mockup modeling the backend, we plan to implement xyz functionality using abc stack". At a hackathon, people get that, and if you show good effort and use of time otherwise you're not going to be dinged on that alone. But faking it to look as if you did more work than you actually did isn't right, and isn't fair to the other hackers.