Just came across this
The definitive answer from NSTCINST 1533.3A: Since the PNS can approve it instead of requiring a NSTC board, like a Tier 1 or 2 to a Tier 3, there's no reason your NROTC Unit shouldn't support you.
For Tier 1 to Tier 2 transfer requests or any academic major change within the same Tier
(1) If the academic major tier list changes, the most recent approved list will apply to academic major transfers.
(2) If a midshipman adds terms (semester or quarter as appropriate) beyond four years by transferring majors, the midshipman will incur the additional costs or gain additional financial assistance per reference (c).
(3) The Professor of Naval Science (PNS) may approve a transfer request if that request is in the best interest of the Navy.
(4) Process
(a) The midshipman submits an academic major change/tier change request to the PNS.
(b) The midshipman must submit change requests to the PNS a minimum of one term in advance of the desired change to facilitate its approval before the midshipman executes a new degree plan.
(c) The PNS reviews submission and either approves or disapproves the request and notifies NSTC OD of the final decision.