Banana Jack Ground Plug Adapter – Anti-Static ESD Grounding for 3-Prong Outlet, Universal Banana Jack Earth Connector for Wrist Straps, Benches & Mats, USA Plug, Black, 1 Adapter

If he is set on actually doing something to fix it get one of these bad boys https://a.co/d/07qxIb7D Plug into standard 120v receptacle and take the pigtail and attach it to the metal case of the computer. In all practice it will be a bonded piece and theoretically shouldn’t shock him anymore

Is the smart switch a dimmer? Try changing it for a non-dimming version. Also it should be grounded and the laptop should be using a grounded (3-pin) power cord and power supply. You could also try just connecting the laptop DC ground (perhaps the shield terminal of the audio out) directly to building ground using something like this: https://a.co/d/0a8A3cNg