Is conscious content available only to the skeletal muscle system?

I applaud Morsella et al.'s approach to investigate consciousness in terms of behavioral control. After all, the function of the brain is to control behavior, and consciousness contributes to the function of the brain. However, I question whether conscious content is available only to the skeletal muscle system, as the principle of parallel responses into skeletal muscle (PRISM) (Morsella 2005) proposes.