This is some of the most non-sensical and convoluted logic in history. Absolutely horrid. I'm sorry man, but it just is.
Basically, what you are saying, is that because of the main event of Wrestlemania 3 ended with an upset victory for the - wait for it - DEFENDING CHAMPION - that from now on, ALL Davids will beat ALL Goliaths.
You systematically neglect the following facts:
1. At WM3, Andre was already out of his prime. This tournament takes wrestlers in their prime, which means late 70's / early 80's Andre, who was a beast.
2. Rob van Dam is not, in any way, and never has been, Hulk Hogan.
3. Hogan is a power wrestler. Power Wrestlers have a chance against Superheavyweights. Rob van Dam is not a power wrestler in any way, shape or form.
Incidentally, by your logic, because the US Olympic Hockey Team beat Russia in the 1980 Olympics, that the NY Islanders and Edmonton Oilers should be winning all the Stanley Cups right now. Furthermore, the Pittsburgh Pirates are now 5-time defending World Series Champions. Why? Because Hogan beat Andre. Isn't that what it's all about?