The BMX world is filled with these kinds of "revolutionary" weight savings ideas. Most everything taken to that extreme breaks. They have plastic BBs, stem/handlebar combos (not good for the harshness of BMX), plastic pegs, plastic everything... things that are drilled out, including frames.
There are some plastic parts that actually do work, like pedals... but most of it is just silly like this headset. For me, I'll just take a dump in the morning and consider that "weight savings".