In this case the AI guy made public which images he used. However, if someone wants, they can simply never publicize what the training set was, copy other arti

In this case the AI guy made public which images he used. However, if someone wants, they can simply never publicize what the training set was, copy other artists and always plausibly deny they used any unlicensed input data, were they to get into legal trouble. I don't really see a way around this tbh.