I barely trust myself to remember something I did or did not do 10 or 15 years ago, I have no reason to trust Lucas' memory of something that happened more than 20 years ago. There's a reason things get written down. It's so we have a record of how something was done or why it was done a certain way. Find one script or novel, from before 1983, that says Greedo was suppose to shoot first and I might believe you.

Until then, I think Lucas is full of it. We won't be able to convince each other otherwise. There's a lot more evidence that it was shot as intended though. The only evidence that we have to the contrary is Lucas' memory (the more time goes by, the weaker the memory gets) and some conjecture.