Earlier quoted context omitted.
His comment was on masks reducing the risk of you getting infected, not infecting others. Which is a selfish point, but nonetheless a correct one.
The masks work, but he only mentions a narrow use that isn't the current reason for wearing them. That's the misinformation; he got you, too. Think of it this way: "Don't wear a seatbelt because they don't keep other cars from hitting you."
Installing an exhaust filter won't reduce lung cancer risk of the driver. Car dealers should be careful if they advertised filters as medical devices that reducing lung cancer for drivers, rather than an filter that reduces pollution for those who live near the road. Exhaust filters are still a good idea for society, but if you want to reduce the personal risk then an air filter for the AC is required. It would however be a rather bad world to live in if everyone installed air filters for the AC and excluded filter for the exhausts.
Outside of garages or other enclosed spaces where the driver might actually get exposed to the cars exhausts.