If he's using a soap recommended by his doctor, you may want to find out why he needs to use such a soap first. Some shave soaps may react poorly with his skin if he has sensitive skin. That could scare him away from wet shaving.
That said, there are plenty of shave soaps designed to be used by those with sensitive skin. IIRC, Cella green is one such soap. However, Proraso Red (and pretty much any soap with a scent) could trigger sensitive skin. You may want to do a search of shave soaps for sensitive skin before gifting your stepson a shave soap.
Excellent points, both. The Major will ask his commanding officer what soap Seth uses, and why he uses it. He just figured the Proraso Red was a good one b/c that particular line works well for his sensitive skin. Also, the whole soap-in-a-bowl approach simplifies things considerably, as it's one less thing to buy or for him to carry to the washroom (shared showers/restrooms in his dorm).