The second amendment includes the word "regulated" for a reason.

The term meant "disciplined" or "skilled" at that time.

The 2A doesn't authorize the militia, that was authorized in Article 1 Section 8, specifically "[The Congress shall have the Power] To provide for organizing, arming, and disciplining, the Militia."

Note that when the Constitution gives the government power it plainly notes as much.

..in reference to the militias, not the arms. Meaning training and proficiency.

Yep, and who gets to set the standards for training and proficiency? And what exactly is a "militia"? Surely it's not random people with firearms. That would not be very well regulated (in any sense), would it?

That reasoning was pretty much explicitly shot down in Heller.

"To promote X, you have right Y" does not mean the existence of right Y is dependent on X.