There are two Federal laws pertaining to sedition.
One is Title 18, Part I, Chapter 115, Sec 2388 "Activities affecting armed forces during war", which deals with sedition in wartime.
The second is Title 18, Part I, Chapter 115, Sec 2387 "Activities affecting armed forces generally", which applies here. Below is this section in question. I have highlighted the parts pertinent.
Title 18, Part I, Chapter 115, Sec 2387
(a) Whoever, with intent to interfere with, impair, or influence the loyalty, morale, or discipline of the military or naval forces of the United States:
(1) advises, counsels, urges, or in any manner causes or attempts to cause insubordination, disloyalty, mutiny, or refusal of duty by any member of the military or naval forces of the United States; or
(2) distributes or attempts to distribute any written or printed matter which advises, counsels, or urges insubordination, disloyalty, mutiny, or refusal of duty by any member of the military or naval forces of the United States
Shall be fined under this title or imprisoned not more than ten years, or both, and shall be ineligible for employment by the United States or any department or agency thereof, for the five years next following his conviction.
(b) For the purposes of this section, the term military or naval forces of the United States includes the Army of the United States, the Navy, Air Force, Marine Corps, Coast Guard, Naval Reserve, Marine Corps Reserve, and Coast Guard Reserve of the United States; and, when any merchant vessel is commissioned in the Navy or is in the service of the Army or the Navy, includes the master, officers, and crew of such vessel.
Any statute or law is a point, and a point has to have a background to make it visible. The constitution underlies all statutes. I think a national effort to deal with an emergency using the military has to be declared under constitutional authority to make this statute visible.