Art belongs to the public, and so do films. They are our cultural heritage, they are bigger than any one person or corporation, and therefore deserve preservation. This is what George Lucas said in 1988 and I agree with him.
George Lucas should have the ethical right to revise his own films, but he doesn't have the right to suppress history. (I would also argue he doesn't have the right to revise other people's films, which is maybe the most disturbing aspect of the SE)