I'm pretty sure that Sedition is the advocating for the overthrow of the US government. Not simply stating that the President is a moron.
There is that part of the Oath concerning allegiance to the Commander In Chief, so any General who want to go public might have to retire first, then go on Fox News and state the obvious.
Uniform Code of Military Justice (UCMJ)
ART. 88 - CONTEMPT TOWARD OFFICIALS
Any commissioned officer who uses contemptuous words against the President, the Vice President, Congress, the Secretary of Defense, the Secretary of a military department, the Secretary of Transportation, or the Governor or legislature of any State, Territory, Commonwealth, or possession in which he is on duty or present shall be punished as a court-martial may direct.
WRONG