Disney has a "Toonfinder" that can always tell you when or if a character will be in the parks and where you can find them. I'm surprised that Universal couldn't give you that information as well. In order to put a character on stage, the position needs to be scheduled, so how hard could it be to let the guest know? Perhaps you should contact their guest relations department and let them know about your experience. I bet that you person you spoke to just didn't want to go to the trouble of finding out for you.
And by the way, I LOVE Rocky and Bullwinkle too.
MiceChat 101: Be NICE! If you don't play well with others, you are in the wrong sandbox.