actually, he does not have to get his GED.
anybody 18 or older may attend California community colleges, earn associate degrees or certificates in any number of trades, and transfer into the CSU California state universities system if they wish, too, to complete BA or BS degrees.
(federal financial aid programs may require the GED or HS diploma, depending, that he would need to check further. But there are also state financial aid programs and the fee waiver program...)