Scholastically qualified does have a specific definition. I recall seeing this some time back, in which each component was given a % of the weighting for determining the WP (or whatever they call it now, another name?). My recollection was that the single most weighted component was math SAT/ACT. (Unfortunately the formula got axed on a bum hard disk. Sorry.) So in that regard, the answer to your 1st question might be more accurately yes. It is definitive, and if there might be any discretion, perhaps in determining the score of ECs. But no discretion in determining which measures count how much.
Other components to WP to my recollection ...rank, grades, ECs/Leadership, verbal scores, recommendation letters.
Your son sounds like top-shelf! Congrats and good luck!
Now, having said all that, allow for what another has said, allegedly based on some research now nearly a decade dated, but perhaps more accurate, specific, and insightful in addressing your question. Note: the Strong Interest is no longer used, as you'd know.
In this paper (2003) author describes the USNA admissions board evaluation process using a metric know as the Whole Person Multiple (WPM). This "score" is calculated based on a candidate's application information. It is designed to be a predictor for successful completion of freshman year at USNA. Qualifying candidate multiples fall between the ranges of 58,000 to greater than 80,000. The paper set forth the components of the WPM and their weighting:
Highest SAT verbal score - 15 %
Highest SAT math score - 31 %
High School Class rank - 21 %
Teacher Recommendation - 8 %
X-curr. activities/athletics - 10%
strong interest inventory technical interest score - 12 %
strong interest inventory career interest score - 3 %
The admissions board can subjectly adjust the WPM by up to 9,000 points.
At least this'll give you a pretty fair idea of how it all goes down. And ...as you can see, this indicates there IS some discretion available for use.