If the universe were at absolute zero temperature, it would indeed be devoid of thermal energy. At such low temperatures, the movement of particles would cease, and all molecular and atomic motion would essentially stop. As a result, there would be no heat or energy available for light to propagate.
In our current understanding of physics, light is composed of particles called photons, which are electromagnetic waves. Photons can be emitted, absorbed, and scattered by particles with which they interact. However, at absolute zero, since there would be no particles in motion, there would be no source of photons or any other form of electromagnetic radiation.
Therefore, if the universe were at absolute zero temperature, it would indeed be completely dark. Without any thermal energy or electromagnetic radiation, there would be no light, no color, and no visible or detectable forms of radiation.