The answer to this is 'evil', at least, ethically wrong. Deception is wrong. It's a good analogy to cybersecurity ethics.
From a law enforcement perspective, this is "entrapment". The professor didn't put wrong answers on the web to questions students could answer, but instead put an unanswerable question on the test to give them an incentive to behave in a way they normally wouldn't.
We have this belief that journalists should misrepresent themselves and otherwise deceptive in order to get at the "truth". In fact, the opposite is true. Almost always, journalists should be honest in their dealings. 
All sorts of professions have the ethical quandary of lying to people for their own good. As far as I can tell, ethics guides always say "no".
I've experience this when reporting vulnerabilities to vendors, who sometimes say "But can't we just lie to our customers because it's for their own good?"
Another example has been "can you leave that material finding out of the report we hired you to do?". In other words, they are asking me to lie. It's a hard one because there's lots of legitimate reasons to soften the language of reports.
But when it's clear they are asking you to be deceptive, the answer should be "no". One good way is to ask them to put their request in writing: i.e. the item can be removed from the report, but will still exist in some other form.
If they aren't willing to put their request in writing, the problem solves itself. You know it's an illegitimate change request, and you shouldn't do it.
As individuals, we are given tough choices where the answer isn't simply "just be honest". Instead, this thread is more about the people we associate ourselves with. When those around you are justifying why they have to lie, it's a good time to reconsider who you associate with.
