Obviously they don't rely on just one type of system for low altitude altimeter measurements, because they just basically told you how someone could go out and

Obviously they don't rely on just one type of system for low altitude altimeter measurements, because they just basically told you how someone could go out and broadcast interference in that spectrum and crash a bunch of planes. Common altimeter system types found on aircraft include barometric, laser, ultrasonic, and GPS. Plus the only time they would be below 2000 feet is near an airport. 5G is limited in distance, thus you could easily establish a no 5G zone around airports and that would mitigate the risk.