Good deal to have a principal nom.
USNA usually doesn’t inform candidates they are fully qualified or “3Q.” The physical/CFA and medical/DoDMERB are the obvious two of the three qual factors. The academic, for want of a better term, generally includes the other aspects of the application that are evaluated. The nom, of course, is an additional admin requirement, and your son has that nicely covered, as principal noms force SAs to offer that candidate an appointment if found fully qualified, no matter how he or she compares to other candidates on the slate in USNA’s own ranking. Technically, the statutory language for USNA doesn’t absolutely require USNA to do this, but they usually do.
I think you can be hopeful but not absolutely certain. You can still wait until April or May, but those elected official slates start getting resolved in Feb-Mar. Continue to tend alternate plans. Your son should answer calls on his phone and set up a professional voicemail prompt, just in case the elected official decides to call (it’s their choice).
We’ll keep an eye on the appointment thread! Good luck!