You got lucky
Your rude, overbearing visitor was actually right, even if he was not respectful or courteous. I hate to defend someone like the fellow you describe but you do need a back country permit to camp at that point. It can be a bit confusing and there are no signs stating that a permit is needed (unlike the back country spots on the north rim) but you do need a permit and the citation is very significant. We camped up there without a permit and the rangers came out and we had to move to the forest area and off the park as we did not have a permit. Two friends that I camped with were not as lucky as they both got cited and still had to move.
You can get a permit via email through the back country office at the park or get it at the park, but then you are taking a chance that the spots may be taken. It is not costly and I highly recommend that you get one before you go out. Don't let the pass requirement dissuade you, it is worth the trip and the little bit of extra effort.
Todd, Havasupai point and Ruby point (Ruby point is the permit you want to ask for at the Back country office) are just east of Bass. As you head to Bass, you will see a hard right before you get to Bass. Take that road and you will end up at Ruby and Havasupai. It really is one of the best spots on the south rim, but unfortunately no longer a secret. Keep cash handy for the reservation pass. The last time I crossed it was $25.
Mikey