Hmm... well, I'm no authority on this (I just like to meddle :P), but Harmy didn't really have any proper theatrical references when he made version 1.0, did he? Subsequent discussions have shown that Star Wars did have some odd colour "issues" from the very beginning.

I don't think that shot of R2 looks wrong per se; if you look at this photo from the Senator screening, the greenish tint is definitely there.

I do know that a photo of a theater screen isn't an ideal reference, but if that photo is at least close to how it's supposed to look, I'd say Harmy knows what he's doing.