Have never met Lucas himself (I did make a short film with his buddy Spielberg one time though but that's another story) however I know many who have worked alongside Lucas in film and business associations over the decades.
Given what they've consistently said, George Lucas is more conservative than most would realize. Part of it is his family background (his father was a rancher who believed in re-investing back into your companies) and George's VERY near fatal car wreck at 16 awakened him to his need for God's purpose for his life, not his own. Had the accident not happened, we probably would have seen George Lucas as a NASCAR driver in the same era as Richard Petty and Cale Yarborough.
He's a complex man. Can't really be pegged as a solid liberal or conservative. But the grief he got from the film industry bigwigs in the Seventies put him in a bind. Either play the liberal game or go home. In the end Lucas left Hollywood and went his own way, but still unable to disconnect completely. It's just the nature of the industry.
Decades from now there will be a biopic about George Lucas. In the right hands, helmed by someone looking for the big picture about his life, it will confound the hell out of a LOT of people who thought he was in "their" camp all along.
If it weren’t for the fact that he has repeatedly stated in multiple interviews, and more importantly, his 1973 story treatment draft for what would become A New Hope (which I posted twice earlier via my Tumblr account), that he based the good guys on the Vietcong and the Empire, the villains, on Nixon’s America, I’d believe your claims that he was closer to a conservative. However, he has repeatedly insisted such was the case, and what’s worse is that this time around, it actually IS backed up by his own handwriting dating back then (plus, apparently Lucas said his philosophy on filmmaking is that “the workers have the means of production”. I don’t know about you, but I don’t think conservatives would actually use Karl Marx as an inspiration for their work ethic.), and based on some of his comments about his ideas on democracy and dictatorships, he actually considers Robespierre’s France, of all things, the best part of the French Revolution, better than King Louis XVI and/or Napoleon anyways.
Besides, as you said, he went his own way and formed his own studio, so he technically had nothing to worry about in that regard if he mouths off, and there are plenty in Hollywood who managed to retain at least most Conservative principles and be open about them without being cast out or blacklisted, like Kelsey Grammar, Kirk Cameron, Clint Eastwood, and Kevin Sorbo, among others.