I understand purist positions, I've taken some on the left before. So I will grant you the assumption that you are no Alex Jones. Liberty always exists within a context, it can bwe revoked lawfully or illegally through vilence which has the power to negate the liberty of life itself.
No ultra Libertarian society grants an individual the freedom to kill one's neighbor if they chose because their barking dog denied them sleep. So Liberty has constraints from both directions.
Americans are under attack daily from scores of individuals with combat weapons. If we called them "terrorists" we would consider ourselves at war with them but we don't; we call them (after the fact) "deranged individuals". so they can legally walk many of our streets carrying assault weapons openly until the point where they actually pull the trigger. At that point it is almost always too late for many lives. A terrorist can not always be identified as a terrorist from causual observation - so too for a dangerous person with a combat weapon. For that reason we do not allow anyone to carry any guns onto planes - is that an "infringement"?
America is now at war, with real fatalities, with a domestic terrorist enemy. They call and consider themselves to be "Real Patriots" resisting perceived current or potential future government tyranny. There are armed movement in many nations fighting their governments. They consider themselvves to be "patriots" in their lands also. but America is a Democracy and our government is elected by our people.
I would say to you that if anyone feels that our people are best served by allowing individuals to prepare for combat against our government, and that to enable that prepartation our country needs to be awash with legally available easy to obtain combat weapons, then they may exhaust every means of persuasion to convince the electorate to keep it so. Those who differ will appeal to the electorate also.
The world has changed and always will change. The most powerful military weapon available in 1776 was a Cannon firing cannon balls. Today we have everything from the H-Bomb to pilotless drones The gap between the weapon systems citizens routhnely kept in their homes and those that soldiers used in overt war has widened immeasurably. Even the Bill of Rights didn't allude to the rights of citizens to keep loaded cannons on their lawns pointed at City Hall, and those days are long long gone.
Today if a government becomes tyranical it is brought down the way the Egyptian people did theirs. The people can not out gun the government, they undermine it through mass actions. Even in Syria guns only flowed into that nation to arm rand the government had lost legitimacy in the eyes of the world ebels after the revolution was already underway, initiated through massive peaceful protests. Ultimately the rebels have strengthened their position through the defection of government military units who brought government weaponry over to the reble side.
Public safety in America now demands public action. It isn't so much any threat caused by citizen militias that brings us to this stage. It is the fact that in the interest of preserving their right to obtain combat weapons they have defended laws that flood the nation with those weapons and through gun show loopholes allow ANYONE to just walk up and purchase them. Guns, like everything else, can and do get stolen. We are sitting on a powder keg in America and the first explosions are already going off.