Well, the script (that he wrote) just says that Han fires and kills him. Doesn't say anything about Greedo shooting.
It's a bit funny that Lucas would even think of something being wrong, or immoral with Han shooting first. After all, greedo pulled a gun on him, pointed it in his face, and said he was going to kill him. (Over my dead body. "That's the idea.") So Han shooting first was self-defense/justifiable homicide here on Earth. No way it could be seen any worse on a largely lawless gangster-dominated outpost like Tatooine.
Also, how is what Han did different than what Obi-Wan did a few minuted before? Evason told Luke he was going to kill him (I'll be careful. "You'll be dead!"), then pulled a gun and pointed it at Obi-Wan (but didn't shoot), and Obi-Wan killed him and his bud. Can anyone explain why that is okay, but the Han thing is not?
Wow. Great point! I have no beef with most of the 1997/2004/2011 changes, but this is one of the changes I don't agree with.