Yes, because the idea is to establish an armed populace before society succumbs to tyranny, not in response to it. The central tenet is that even if a society is run by Quakers now, it won't always be, because in the absence of proper inputs societies tend to decay to their stable basal state which is despotism. When that happens, the population must be armed in order to revolt and restore a democratic system. I would even say its better to arm the populace while the government is still Quaker because that would establish the proper cultural mores surrounding gun ownership in an enlightened environment - e.g. knowing that gun ownership is a responsibility and right, connecting it with ideas of liberty and civic duty, viewing them as a last resort, learning about guns from your father and not your homie on the corner.

You need to have the population armed beforehand. Its not practical to try to dynamically adjust how armed the populace is in proportion to perceived governmental Attila-ness.

To your last point, an armed populace makes revolt feasible, and there is a spectrum here. The key is that the oligarchy will need to convince the army to stay on its side and punish the revolting populace. The more sacrifice and violence that is required, the harder it is to keep convincing them. Also, look at the insurgencies in Iraq and Afghanistan: an armed, hostile populace is just much harder to control than an unarmed one. It dramatically increases the cost of every excursion from a military base, the number of soldiers required to subjugate an area, etc, and the grand lesson from those conflicts is that boots on the ground are still needed to control an area, and that technological solutions like drone strikes still don't scale well enough and aren't cleanly targeted enough to change that. Perhaps that will change in the future, but I actually suspect that the prevalence of consumer drones will maintain the power of the public to resist the military. Look at Ukraine and Russia; the dominant weapon system now is the consumer drone, eclipsing even artillery, which has democratizing implications for the future of the tug-of-war between societies and their governments.