Clearly not, because the color grading on all previous home media releases has been way off.
First of all, if those releases look bad it’s because they didn’t use color references, not because they didn’t have
any, the 2004 release looks awful because George was out of his mind, and the 19SE looks like that because they brought in the colorist from The Mandalorian to grade the trilogy according to the saga’s new style: dark, dry, monochromatic, and cold, unfortunately, and using a base from the canceled 2012-14 3D release, from which they abused DNR, removing details in many places and making many shots look blurry. But they must have color references.
The separation masters are generally made from the raw negative, so those wouldn’t be color graded. Only the interpositive and later is color graded.
So what? Even if the separation masters come from an unaltered OCN that hasn’t undergone color grading, they’re still a better color sample than any other material. While they don’t have the exact colors that were seen in theaters back in 1977, they still provide proof of how it looked on the OCN before degradation.