And if a person is using a model based on harmful training data, they should be held responsible.
I will have to disagree with you for several reasons.
You are still making assumptions about a system you know absolutely nothing about.
By your logic anything born from something that caused suffering from others (this example is AI trained on CSAM) the users of that product should be held responsible for the crime committed to create that product.
Does that apply to every product/result created from human suffering or just the things you don't like?
Will you apply that logic to the prosperity of Western Nations built on the suffering of indigenous and enslaved people? Should everyone who benefit from western prosperity be held responsible for the crimes committed against those people?
What about medicine? Two examples are The Tuskegee Syphilis Study and the cancer cells of Henrietta Lacks. Medicine benefited greatly from these two examples but crimes were committed against the people involved. Should every patient from a cancer program that benefited from Ms. Lacks' cancer cells also be subject to pay compensation to her family? The doctors that used her cells without permission didn't.
Should we also talk about the advances in medicine found by Nazis who experimented on Jews and others during WW2? We used that data in our manned space program paving the way to all the benefits we get from space technology.