That is great news!
Sounds like he is being offered an AOG (WP Associate of Graduates) scholarship!
Basically, candidates who are offered this are QNS with a nom, usually with strong leadership.
The AOG will pay for 1/3 of the costs to go to one of 4 Civil Prep schools ( MMI, Valley Forge, NMMI and Greystone) for one year and then reapply. The school pays 1/3 and the candidate pays for 1/3.
Only about 50 are offered/yr (think of it as 1 per state) and are offered to either scholar/leaders or recruited athletes (recruited athletes go to a sports specific school)
Pass your classes, pass the CFA and remain medically qualified and you will have an extremely good chance of being offered admission in the next class at WP.
Here is a link that describes the program:
http://www.westpointaog.org/page.aspx?pid=4578
Your DS must be viewed as highly desirable candidate but for whatever reason (very competitive district?) , WP may not be able to offer him a spot in this year's class. This is pretty much the next best thing.