Well, it's also the date that REVENGE OF THE SITH was released in 2005, and I think everybody agrees that THAT was the better movie (at least I think so).
You could always tell you friend to just mention that instead.
This is true, and I'm almost certain he knows that, but for some reason he only acknowledges Episode I and May 19, 1999. I think it's because he, I and others were up to our eyeballs in Prequel countdown overload and all the things associated with it and it's always been a special time for him. I can't blame him, really. 1999 was like one giant nerdgasm for most sci-fi/fantasy fans that I knew and came into contact with.
That said, yeah. ROTS is clearly the superior film.