MPA or the like. There are excellent grad programs for people who want to do that sort of work. Cheaper and shorter than law school, and actually teaches the skills necessary for the job. Also, internships and connections from faculty will be vital for getting a job in that field. Law school will give him none of those things.
He should get a masters and work experience (preferably both at the same time). Then, in 5 years, see where he wants his career to go and whether he absolutely, positively needs law school to do that. Then, and only then, should he go to law school.
The only people who should go to law school are those that want to actually practice law. For anything else, a masters will do.