Tournaments are often cut throat but, for me at least, good sportsmanship counts for far more. Helping a new player by over looking honest mistakes is cool; I am not saying that you should allow someone to take advantage of you either. I know not every agrees with that idea though.
Have you every played Go or Pente? In those games if you are about to make a move that will let you win in a couple of turns or if your opponents misses something that would let you win, the proper thing to do is tell your opponent. That is how it is suppose to be played. The idea is that to truly a win it must not be though mistakes but by strategy; your's against theirs. Winning because your opponent missed something really isn't a win at all since you are probably not really the better player/strategist.
But as I said above. Tournaments are a different beast all together and often cut throat. I think you did what was right for you and that you should be proud of a well played game, even a loss.
Edited by Ken at Sunrise