I’m sure he knows that he can go back, do the army, and probably serve in some capacity that would highly strengthen his US applications. There is tremendous opportunity for young people to do high-level work in the Israeli army, get fantastic training, quickly become officers. Israel also has several excellent institutions for what he wants to study. But he doesn’t want to do the army, and once he’s 18, if he goes back, they’ll grab him for the military, and it won’t be for doing anything high-level. You are right that he cannot work legally here until he gets his green card - but doing a voluntary research-internship is a time-honored tradition to establish credentials for college applications! If his green card comes through before next December, which it sounds as if it surely will, he can apply RD as a US resident, as opposed to as an international student, and qualify for financial aid, and for acceptance as a US resident. So in my mind, doing a gap year to do an unpaid research internship, which might be able to be converted to a paid job as soon as the green card comes through, and apply next year with an application strengthened by both the research internship and his new status as a US resident, seems to make the most sense.