Okay, so the scale at which they sale their service is a good argument that this is different from a human learning.
However, on the other hand we also have the scale at which they learn, which kind of makes every individual source line of code they learn from pretty unimportant. Learning at this scale is statistical process, and in most cases individual source snippets diminish in the aggregation of millions of others.
Or to put it the other way round, the actual value lies in the effort of collecting the samples, training the models, creating the software required for the whole process, putting everything into a good product and selling it. Again, in my mind, the importance of every individual source repo is too small at this scale to care about their license.