The problem with your argument is that the militia was designed for a specific purpose within the Constitution.
We know what the purpose is, because they wrote it down.
It's in article 1, section 8
- "To provide for calling forth the Militia to execute the Laws of the Union, suppress Insurrections and repel Invasions;
- To provide for organizing, arming, and disciplining, the Militia, and for governing such Part of them as may be employed in the Service of the United States, reserving to the States respectively, the Appointment of the Officers, and the Authority of training the Militia according to the discipline prescribed by Congress;"
The milita was designed to prevent lawlessness at the FEDERAL LEVEL. i.e. the feds could call up the militia for this purpose. Remember, the Bill of Rights didn't apply to the states at this time, only the Federal govt.
So, if a state couldn't handle the job, then the militia could take over.
That's not to say that the militia didn't do it at a state level, that's besides the point here. We're talking about the US Constitution and not state constitutions.
This means the 2A is also based around this intention.