There is no possible basis in law for copyright infringement.
Copyright infringement isn't "you can do these things with copyrighted materials and everything else is banned". It's "these specific things (redistributing substantial portions of published works) are disallowed, unless you meet exceptions, and anything not explicitly disallowed is legal".
You are unconditionally allowed to learn from copyrighted works. There is no legal basis for preventing it. There is no possible basis in copyright law preventing it. It would take new legislation restricting doing so, and it would be impossible to apply to any training that happened before this new crime against humanity of a law was written.