There are too few hard facts to allow clear hypotheses. Some however might be:
1). Armond and Arik really do want to play football together;
2). This is a much bigger decision for Arik than it is for Armond, and the whole family realizes that;
3). USC claims that Armond has a medical condition. Such a matter, even if disputed, would have to be "cleared";
4). Armond would have to transfer as a graduate student rather than an ordinary transfer. Such standing would also have to be "cleared";
5). both brothers preferred to EE, knowing that immediate playing time is enhanced by such a decision.
#s 2,3,&4 seem to have caused great stress, and ultimately trumped #5. #1 seems to stand as the dominant criterion. Since they act as a family, I will bet that #2 will be the second dominant criterion, so that any school wanting the brothers needs to REALLY sell itself to Arik.
Armond's continuing this semester at USC "solves" potentially several problems:
a). it gives time for the mysterious clearances to be cleared. They, however MUST be cleared by NSD in some concrete or matter-of-trust way, or Arik will not know what his brother's actual options are.
b). if classwork is an issue, Armond doing selected work at USC could clear the academic business of grad school entry if such exists. This clearance would be as a handshake matter-of-honor: if you do this we will admit you.
c). something similar could go on with the mystery medical issue: if we do this, and this is the result, then our medical staff has no problems. Armond would then have the entire semester-plus to clear things under the handshake agreements, but Arik would still have to announce by NSD, also in a manner of trust. Arik's announcement would reflect which school gave firmest evidence of clearing Armond.
d). despite the clearances issues, the only institutions involved would be those institutions offering Arik the best situation for him. It's HIS four-year career that's primary.
One speculation. Maybe it makes sense in some parallel universe anyway.