I know you're not a lawfag, so you'll get one pass. The Militia is the people. Also the , is a clause break. Meaning the right of the people to bear arms shall not be infringed is a separate statement
by itself.
But yes, none of the changes he's proposed hurt the 2A. The background system is already in place, but a lot of states don't actually report the information. Simply enforcing that would fix it. The age limit is semantics. The 2A doesn't guarantee an age to use. And the bumpstocks are broken aftermarket objects not a physical part of a firearm so they're not protected. Why use something that causes jams?