You might want to ask the mods to move this to the Publicly and Privately funded Military College forums because those posters typically will have more insight into how the SMCs work.
Otherwise, I think everybody here will glom onto 2 key words in your OP...NROTC scholarship.
As stated as a contracted mid(scholarship) you will sign commitment paperwork the beginning of your fall semester junior year stating you will serve out your commitment in the Navy. Thus, that means you would have to ask to be x-commissioned into the CG, and if it is like x-commissioning within the DoD world, the CG would also have to agree to accept you too.
~ CG is part of Homeland Security, not the DoD, so now, unlike trying to xcommissioning between DoD branches (Army, Navy or AF) you are also asking the DoD to completely release you to serve in Homeland.