If he's just getting it to meet requirements to sit for the CPA exam, and has an undergrad in accounting already, I'd say just get it at whichever is cheaper. (including COL)
The two schools' reps are comparable, for the Macc. There might be more recruting at UH, as there are definitely more public accounting firms in Houston than SA, though. That said, however, I know a few folks from Trinity who have all had internships (and/or full-time jobs) with the large firms around Houston, so...
If he does lean towards UH, tell him to stick with the central (Cullen Street) campus. The Clear Lake campus is primarily for working commuters, and the Downtown campus is the redheaded stepchild of the local system.