JHU is very strong for international relations/political science, too.
In terms of political activity (thus opportunities) during his junior/senior years, Emory is worth looking into.
Perhaps GMU, JMU, W&M, and other universities in Virginia.
Look into Dickinson, Kalamazoo, and of course Macalester.
UMass Amherst would be the right size, especially if he can get into the Commonwealth Honors College.
Same thing for UMD-CP, although it’d be larger.