Non-violent political resistance only works if there is an effective appeal to a third party. Compare the situations of the demonstrators at UC Davis vs. those demonstrating against the regime in Syria. At UC Davis, a police officer pepper-sprayed peaceful demonstrators at point blank range, leading to his own suspension from the force and a university-wide review of protest-related policies. In Syria, demonstrators are routinely subjected to beatings and tear gas, not to mention having the secret police kick their doors down in the middle of the night, but the perpetrators have the full support of the regime. A sufficiently well-armed and amoral regime will always be able to suppress dissent.
True, third parties are usually neede in those extreme situations. But let's return to Aikido and violence.
What principles are those third parties using to do so, to prevent violence. What path are those people treading. It's certainly not the art of war. Yet if successful they save many lives.
P.S. The soviet union to my reckoning was sufficiently well armed. It depends on the scale of uprising I suppose. But once again we are talking extreme situations.