Caltech does not offer merit aid, nor does MIT or Princeton. The real question for schools like that is…is any undergraduate degree worth a quarter of a million dollars?
I don’t know how good he is in swimming, but Cal Poly is worth considering. They compete in the Pac12 for swimming, but all of their athletes are students first, and have to meet tough admissions standards. That may make it a little easier to get a spot. They have a very strong Aerospace program (best in the nation according to Aviation and Aerospace Weekly, for whatever that’s worth). It is its own dedicated department with concentrations in aeronautics and astronautics. They have a good physics department too. Several things set them apart. They do not offer PhDs, so almost all of their resources are directed to undergrads. In the college of engineering alone they have more than 80 labs. They have small class sizes and all classes, including labs and discussions are taught by professors. They give very little merit. My similar stats son for example got $2k/year at Poly, but $25k per year at Case. The kicker though is that the total COA at Cal Poly for OOS students is $36k/year.
Fun times. Good luck!