I thought he meant it the other way around. Since militias are not required for the security of the state, citizens don’t need to bear arms.
If you’re a male American citizen of a certain age, you are in the militia. Thats what “militia” means—it refers to the part of the citizenry capable of military service.
Fair enough as it's a very loose definition and doesn't require formalities or any kind of actual restrictions on the right.
Historically it did. The Second Congress passed two Militia Acts in 1792, the second of which mandated that each member of the militia buy a musket or rifle along with ammunition and other kit, and to be organized into specific units as directed by their state legislatures.
Basically every able bodied citizen male is in the 'unorganized militia' anyway per US code.