Not to mention the assumption that the US army consists of a group that would oppose citizens standing up to the Government.
You're more likely to find support for the 2nd, as currently interpreted, among current and former army personnel and current and former police officers. Having purchased and sold weapons privately with current/former military and police officers, hunted, and target praticed with them, I get the feeling most of them don't have a problem with people owning and carrying weapons.
Sure. But this renders the argument for the 2nd irrelevant. The argument that civilians need guns to defend against tyranny assumes that the armed forces remain under command and control of the tyrant, and that the armed civilians can defeat them - which is fucking insane.
If the armed forces agree that a rebellion should occur, then whether or not civilians are armed is irrelevant.
The army have plenty of guns, with or without the 2nd amendment.
There are four possible situations:
Army and civilians support the government - no need for civilians to bear arms.
Civilians support the government, army doesn't - army crushes civilian resistance and seizes power in military coup. Arms bourne by civilians are irrelevant because the army has more guns, better training, better weapons systems, etc.
Army supports the government, civilians don't - army crushes civilian resistance and keeps government in power. Arms bourne by civilians are irrelevant because the army has more guns, better training, better weapons systems, etc.
Army and civilians rebel against government - army crushes government resistance and seizes power in military coup. Arms bourne by civilians are irrelevant because the army has more guns, better training, better weapons systems, etc, and civilians add too little to matter either way.
In no case does the right to bear arms (or the absence of that right) change the outcome.
The second amendment is completely irrelevant to the deposing of tyrants; any argument for the 2nd must be based on some other benefits, because deposing of tyranny is a non-sequitur.
Unless you get rid of the US military first. In the absence of a powerful standing army, the argument makes sense. But the US now has such an army, so it no longer makes sense.
There may be good reasons to keep the right to bear arms; but this cannot, logically, be one of them.