I've always assumed it's meant firmly tongue-in-cheek, but it's very morbid humour. But it's also a reminder of how powerless people in the past still managed to take action to rectify injustices, even if it happened in an overly brutal manner. In free, democratic societies, people should have more power to create the change society needs, but it doesn't seem to be working.

But it's also a reminder that if the powerful people in society offer too much resistance to the change the people need, at some point the only way to get that change is by extreme overreaction.

Personally I'd rather see the revolution happening by the soap box or the ballot box rather than the ammo box, but when media and voting systems get gamed and corrupted while people's rights and needs keep getting trampled upon, at some point a more violent solution may become unavoidable. But that's going to be very hard to steer and have many harmful side effects.