The USCG IS military, NOT "can be militarized".
That's complicated. For instance the Deployable Operations Group -- despite being a recognised special operations group -- was not considered part of USSCOCOM because they were not part of the military chain-of-command at the DoD (unless specifically transfered there during wartime as noted).
At least that's what my DD-214 says.
That's certainly interesting, that suggests -- not unsurprisingly given the ability to transfer between USCG and USN units and use of USN Staff Corps officers in certain roles in the CG that individual personnel are considered part of the military and the active duty military at that (National Guard personnel are issued with NGB-22s instead and NOAA & PHSCC use different forms again) despite the Coast Guard not being administratively part of the military. Presumably this is due to the USCG still holding authority under Title 10 (as a member of the armed forces) as well as Title 14 (as a law enforcement and rescue organisation).
At the end of the day, whether or not the USCG is military or non-military "armed force" isn't the most important point as a parallel to Starfleet, but rather that it is definatively an organisation that is other things first and even second, and that third which is an on-point description of Starfleet.