I think I see what he's thinking. In the 50's and 60's (when all headlights were round) there were auto aftermarket louvered headlight covers to accomplish this task. The louvers themselves reflected enough outgoing light to make the oncoming car legally visible but the blinding glare was gone. They were not popular (probably) because they looked funky. With todays aerodynamically shaped headlight covers they would look bad. Headlight lens polarization should have about the same effect and would be almost invisible. Now that I think about it, I'm not sure if they aren't already doing this because I'm 62 and, with the exception of the new xenon headlights, oncoming glare doesn't bother me as much now as it did in the 50's and 60's.
Short true story;
In the 50's I got to ride with my uncle in his new semi. He had an absolute hatred for people who drove with their blinding high-beams always on. He had bought the most powerful hand-held spot light on the market to point directly in their eyes as they passed coming from the opposite direction. He said it was "to teach them a lesson". As the first one with high-beams on approached, he started cursing in rage as he positioned his spotlight for the counter attack. When the other car came within range he screamed "TAKE THIS YOU IGNORANT SON OF A !*%$##!!!!!!!!! and the instant the spotlight switched on and hit the oncoming cars windshield smack dab on the drivers side, you could read the big bold letters across the top of the windshield of the now out of control car "STATE TROOPER".