MSNBC did a nice hit piece on the teen suing to expand his 2A rights. They interviewed CSGO mouthpiece Ladd Everitt who stated that, outside of the personal attacks, his opposition to this is that is has been proven that 18-20 year olds aren't developed mentally enough to handle firearm ownership. He moved the goalposts when it was brought up that they can serve in the military since they receive training and are supervised.
So since there is no training or supervision for voting, why should people not developed mentally be able to determine how the nation is run? Obviously this is just a recipe for disaster.