I think you might be mistaken. XRR wheels actually come in GT Silver with colored Porsche crests, or in the exterior color (and also colored Porsche crests).
They cannot be ordered without colored crests.

You must be thinking of Gnil's Seal Grey C4S, which indeed has Seal Grey wheels. I guess he had forgotten to mention which option he wanted, so they went ahead and went for the latter without asking.

Edited: Damian just beat me