the "try" not to use IMDB rule also states this:
3. Try not IMDB'd the trivia questions. I will try for these questions to remain relatively easy or to pertain to popular movies.
So, one could say the question wasn't "relatively easy" and justify using IMDB.
As Sebastien said earlier, there is no way to police people to see if they are using IMDB. IMO we need to have a mix of questions, some of which you can't find the answer to unless you know what you are searching for.
The last thing this site needs is for us to start picking apart "the rules"