This is a tortured misreading of what I’m saying - and regardless is addressed by my argument.
> you are discouraging people from taking actions which might reveal such knowledge to them
If you are deliberately and knowingly avoiding that knowledge to escape culpability then that’s morally equivalent to having the knowledge but failing to act. A police sergeant who says “get a confession, and if you rough him up don’t tell me about it” might be protecting themselves from legal responsibility but certainly not moral responsibility.
Again: there isn’t a loophole here. Constructing a loophole is itself immoral.
> By your logic, an activist that knows about the conditions inside the plant is also responsible for the safety of the workers
No - the manager has substantially more capacity to act than the activist. There is some fuzziness - is the activist is deliberately suppressing information about conditions inside the plant then they do share responsibility. But if the activist is merely ineffective then it’s not reasonable to blame them for injuries or fatalities. This is not a question that’s amenable to algorithms or flowcharts, which seems to be giving you some difficulty.
> and no action other than successfully protecting the workers will satisfy that responsibility.
This is not what my logic said at all! It’s such a ridiculous misreading that I wonder if you are arguing in good faith. I didn’t say the manager had to successfully protect the worker, but that they had to try. If machine maintenance is the responsibility of another team then perhaps the manager could do everything right and still have a worker killed. No one human can solve every problem that might come up. But if the manager knew there was a risk and did nothing, not even taking a look, then they share moral responsibility with the team actually responsible for maintaining the equipment. There is a huge difference between “the firefighters failed to stop the fire because it got too dangerous” and “the firefighters failed to stop the fire because they went out drinking,” even if in the latter case the fire was hopeless.
Again - you really can’t lawyer or logic your way out of moral responsibility, even if it works on a legal or social level. And no, there isn’t a foolproof algorithm for determining moral questions like this. But if your approach is “where are the gaps in this moral framework that lets me get away with bad things?” then you are not interested in acting morally.