OK
The Coast Guard in both peace time and war time is ALWAYS under command of the Commander-in-Chief.
Top and bottom do not a chain make. In time of peace it goes from the CIC to the DOT and down. In time of war it goes from the CIC to the DOD and down. Go back and look at that little history of yours; they transfer the department in time of war and it reverts at the end.
One path is military, one isn't. That does not mean that the organization management procedures aren't military in nature, because of course they are. I think we are arguing definitions of what constitutes "military."
The Coast Guard is ALWAYS subject to the USCMJ, at peace, at war.
The USGS personnel are when at sea or on US property, but I am not certain that applies elsewhere. Maritime law makes sense as they wouldn't want to be flopping internal procedures every time there is a dust up abroad. Are you suggesting that if I am arrested as a US citizen by the USGS in time of peace that I get a military trial? Sorry, I don't buy it. There are other differences from standard military practice. IIRC, if a documented boat is at the dock, it can only be boarded by a US Marshall and not the USGS alone, but then, they may have changed the rules... probably without an act of Congress. That's the problem.