That's incredibly interesting because in the AFROTC jr yr they will go up for their AFSC board (career). The AFSC comes down @ Feb/March. Now they are saying in Sept of their jr yr, after FT they will test them. That means IMHPO cadets who have a desired career field could be f'd. I would as a parent ask if they superscore the AFOQT, or if their file shows they took it twice.
Unless something has changed dramatically an ACT does not matter for OTS/C because to apply for OTS/C you must be a college grad and the ACT at that point is not a player since that is a marker for college admittance.
Now, if you are looking at on a whole the ACT is a good test to use compared to the SAT because the ACT has a Science section. The AFOQT will have flying situations within the test, which is akin to a Science orientated mind. The SAT does not have that program/philosophy.
It is also important to understand how the ROTC system works. It is very sim. to the AFROTC scholarship program. You will need the gpa, the AFOQT, the recs and the ECS when you go up for the board as a C300. Carry a 2.6 gpa in engineering with a 96 on the AFOQT, but never held a position in the det and no ECS, you are not going to fare well. Carry a 3.4, 89 on the AFOQT, det commander and ROTC command support you will be sitting prettier.
Getting a scholarship is only one step in a the 4 yr process.