The reason that he says fear of the government is unfounded is because the citizens are armed. The idea was groups would come together and make their own militias. These wouldn't be government run, which makes sense considering that's how they got rid of the British. While there was a standing army, there were militia that weren't getting orders from Washington. Considering there was no mass communications at the time, it would have been very counter productive to have the States control the arms. The idea someone from the State would declare an emergency and hope everyone would get the message.. and make it to the arms.. and hopefully spent time training (something Hamilton said wouldn't work out as requiring people to not work to train would be disastrous for the economy) .. and get organized would allow way too much time for the other side.
From 46
"To these would be opposed a militia amounting to near half a million of citizens with arms in their hands, officered by men chosen from among themselves, fighting for their common liberties, and united and conducted by governments possessing their affections and confidence. It may well be doubted, whether a militia thus circumstanced could ever be conquered by such a proportion of regular troops. . . . Besides the advantage of being armed, which the Americans possess over the people of almost every other nation, the existence of subordinate governments, to which the people are attached, and by which the militia officers are appointed, forms a barrier against the enterprises of ambition, more insurmountable than any which a simple government of any form can admit of. Notwithstanding the military establishments in the several kingdoms of Europe, which are carried as far as the public resources will bear, the governments are afraid to trust the people with arms. "
For the self defense part of 2A, IDK.. I'm not sure defending yourself is a 'right' that needs to be spelled out. I don't think 2A really covers it directly, but if you look at that time (not tech.. just the concept) it makes sense that the people writing this up would expect everyone to use guns to defend their homes and well being. There wasnt a reliable way of calling for help, and I shutter to think how long that help would take. It's bad now, I can't imagine it then. Most states have covered (if not all.. I haven't looked too deep into other states past my own) self defense with laws allowing you to match the tools being used to threaten your life. I know I personally feel if someone's shooting at me, I'd like to be able to shoot back. YMMV greatly though.
Having said all this, as I've said before, it's very possible that 2A is out of date. Communications and other tech have developed making gaps less and less important. I highly doubt it'll ever be overturned in my lifetime, but it's very possible.
No offense, but this reads like more "My team is the good guys and anyone else is the bad guys team" bullshit that chokes politics. There are many democrats I personally know that own guns, myself included. I can get why it appears that way right now as the only guns you're hearing about are those that are very misguided on how society works and are going out of their way to start/escalate shit. You're still seeing a small portion of gun owners though.
As for the kid, that wasn't vigilantism.. that was pure murder.