I think the program doesn't matter much if he does well in showcases. However I would definitely advice against quitting the last year. HS season is short and he still has enough time to play showcases or travel in the summer and fall.
It doesn't have to be that way but some college coaches could see not playing the last HS year as a character flaw or a case of too much entitlement/being a "diva". Maybe he could explain that but I wouldn't take that chance. Just play those 3 or so months, be a good teammate and have fun and then get back to work in the summer and fall showcases.