No, and your understanding of it is not reflected by the SCOTUS. You do not need to be in a militia to benefit from the 2nd Amendment or access it.

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.

Basically every able bodied citizen male is in the 'unorganized militia' anyway per US code.

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.

The Bill of Rights (i.e. the first 10 Amendments) are individual rights. There's plenty of commentary about this, but quoting from the ACLU in particular:

  "The entire Bill of Rights was created to protect rights the original citizens believed were naturally theirs."

https://www.aclu.org/documents/bill-rights-brief-history

The Bill of Righte contained 12 proposed amendments, 11 of which have been ratified.

We've just gotten used to calling it the first 10, because the other one took a long time to ratify.