OpenAI is obviously using libgen. Libgen is necessary but not sufficient for a top AI model. I believe that Google's corporate reluctance to use it is what's holding them back.
How do you know? Has someone created a set of test questions that can definitively prove it one way or another?
I don't believe it's even possible to create such a set of test questions. You would need to specifically test for differences between the versions found on Libgen and those that aren't available there. But even then, the evidence would be inconclusive.