One of the implications of this report is absurd. Why does the Surgeon General feel the need to clarify that one particular aspect of cannabis is deleterious, when their stance is that the substance is Schedule 1?
Ultimately because of the CSA the attorney general is responsible for all decisions on scheduling substances. By the letter of the law, they're supposed to consult with HHS and by extension the surgeon general, but in reality, it's a rubberstamped process largely controlled by the DEA.
The Drug Enforcement Agency and Food and Drug Administration set the drug schedules, and the Surgeon General is under the United States Public Health Service Commissioned Corps.