I do think trademarking a color is ridiculous. However, I read something before (likely on HN but I can't find it now) explaining the value companies like Pantone provide. When Pantone "publish" a color, they define how this color will look when displayed on different media, printed, digital, on concrete or on wood, or under different lighting conditions including UV or IR, etc etc. It's a lot more than just saying "I own #AABBCC".

I don't know the specifics of this case, but this looks like it falls firmly into the category of "I'm egotistical" as opposed to the "I am providing additional value" category.