All of you guys make good points about getting a degree in a different field. His options, however, are very limited due to the Post 9/11 GI Bill. I myself am in a similar boat when it comes to uncle sam paying for flight lessons.
The Post 9/11 GI Bill will only pay for lessons when it is apart of a school's degree curriculum. In order to have tuition and flight fees covered he must be enrolled in a school that offers a Aviation degree with flight as a core study. This only leaves him with 2 real options:
1) Enroll in a community college that offers a A.A.S Degree in this study and after you have completed the degree with flight certs - major in other field. The only down side is that he would have to pay out of pocket for 2 years worth of school to complete the bachelor's degree in a field of his choice.
2) Enroll in a College or University and Major in the Aviation Field and get your bachelor's degree. Any school thereafter is paid for out of pocket.

I think option #1 is the best way to go. Completeing the Flight certs and working to a different major will be the best for him. He should be able to get a job as a CFI while attending school for a different degree. This means income from the CFI job and Income from the GI Bill's Housing allowance. Build flight hours - get paid - go to school