I went back and forth with Mr. O'Heir about that claim in PM's, and he is stuck in the past with the idea CC's are defined by the volume of a gram of water, which was true between 1901 and 1964. However, when it was discovered different isotopes of water didn't match the volume, plus the temperature had to be at maximum water density, which occurs at about 3.98°C, and as water is very slightly compressible it also had to be at exactly one standard atmosphere to be true, in 1964 the original 1795 definition of a liter as 1 cubic decimeter was reverted back to and the cubic centimeter is just 1/1000 of that. The standard meter (metre, in International Bureau of Weights and Measures spelling) is now defined as the distance light travels in 1/299792458th part of a second in a vacuum, and so a cubic centimeter is a cube whose side lengths are defined as the distance light travels in 1/29979245800th part of a second in a vacuum. So it is not dependent on liquids anymore.
But even if the definition were dependent on liquid water at a certain temperature as the fluid ounce still is (the volume of an ounce of water at 212°F), there is nothing that stops anyone from measuring flour or other dry goods in those same measures. So I fail to see the relevance a volume being a liquid measure anyhow. It just doesn't matter to the proceeding.