But this is a completely different film, and you presume he wanted the R rating.. It was never intended for children to begin with. Many adults don't even get it. It's a niche film, so why should Lucas care about the rating?
"The 1997 board was definitely more conservative than the 1977 board, and GL may have done it as a pre-emptive strike."
Films aren't going to be re-rated unless they are re-submitted to the review board. Films with the term "Unrated version" simply weren't reviewed - that's it. This is why most DVDs have thei extra content labelled "unrated". Besides, Lucas doesn't say anything about changing Greedo in order to keep its rating, and McCallum just recently stated that they won't change ROTS if it receives a PG-13 rating, so there's really no basis to this argument.
"As for Spielberg and the guns vs. walkie talkies, terrorist vs. hippie, etc., none of those changes would have changed the rating."
Neither would Greedo shooting first, or burning bodies. I'm still wondering where this belief that "he showed the burning bodies of Owen and Beru Lars in 77 to get a PG rating" reasoning is coming from. Seems someone is ignoring the fact that there are many other troubling scenes in ANH, such as Vader choking Antilles, Luke fighting the Tusken (a rather intense scene, even for '77), Alderaan being destroyed, Vader striking down Obi-wan, various pilots being killed face-to-face with the audience or crashing spectacularly, etc. All of which would have blown any chances of a G rating out of the water. Don't tell me that all of these were added simply to avoid a G rating as well...