Greer is, indeed, her GAL at present. He was written up as such in a puff piece called "The quiet judge" or some such piffery. In that same article, it turns out that Greer is responsible for another woman's death--he refused to issue an injunction on a menacing man in a woman's life, and she ended up murdered by him a few days later. Nice thing about being a judge is that you can't get sued for malpractice.
I don't believe that's right about Greer being the Guardian ad litem. He's the judge who has abjudicated this matter between the Schindlers and Schiavos.