I find it hard to believe the the 2nd Amendment is exclusively for national defense

[jimmy the one]

22. 2ndA is obsolete & antiquated

N-Unicorn: I read in another thread that the 2nd A was enacted to.. The author of the opinion went on to say that the 2A was in no way meant to be a guard against the government.
I find this incredible because looking at the rest of the Bill of Rights every amendment is one declaration of "we don't trust government" after another.

I think you might be conflating two separate concepts. Firstly, the author you mention probably meant to say the 2nd amendment's purpose was not to guard against a tyrannical domestic, or perhaps foreign govt, dunno his intent.. You might be conflating this concept with the bor amendments being restrictions on the govt (congress) - what you called guarding against govt; do you think this the case?

uni: I read in another thread that the 2nd A was enacted to create a militia in lieu of a standing army but with the advent of modern militaries we no longer require militias for national defense ergo the 2A is obsolete.

Not only that, but since the 1903 militia act, there has been no 'well regulated' citizens militia as spelled out in the 2nd Amendment. Since the rationale for RKBA has collapsed into oblivion, so should the 2ndA, since it has become obsolete & worthless. You no more need the 2ndA to purchase a firearm today than you need first amendment rights to talk to yourself.
.. Today, the 2ndA emboldens americans to be able to own & practice with military style assault rifles, while not ever being obligated to serve one, single, day, in a well regulated militia or army or navy or national guard unit. To suggest this was the intent of 2ndA is absurd.