One of the things that often strikes me about questions about responsibility is that people who are not taking any responsibility at all tend to claim that they think that an aikidoka isnt taking enough reponsibility. Of course it is easier to attack or doubt someone elses responsibility instead of taking some responsibility yourself.
As for the responsibility of the aikidoka, well, we are not the guardians of the world, we are not police, judge and executioner in one. We are only human and can do nothing more than that. And every theoretical situation has a lot of theoretical drawbacks. Fortunately we only have to deal with reality and often do so without being aware of it anyway.