The reservations person was just trying to save you some money. There's nothing wrong with that.

While room nights booked using the convention code (and paying the convention rates) are important for the club in securing good deals for booking the convention, they aren't mandatory for every attendee. It's kind of a double-edged sword. Booking with the convention code helps the club, but at the end of your stay, you can't have your room retroactively comped based on your casino play. Booking through the hotel using direct offers from them will allow you to have your room retroactively comped based on your casino play, so it becomes a matter of each attendee's budget.

I haven't firmed up my convention travel plans, but if I can swing a five or six day stay, I'll book three nights using the convention code and book the other two or three using South Point offers that I receive in the mail on a regular basis. I'll be doing it this way due to a tight travel budget. This way I'll be supporting the club the best way I personally can while still keeping the trip affordable.