

That is not what judges have said. They’ve said that merely training on text is not a copyright infringement. However, companies that downloaded enormous amounts of pirated texts (i.e., stuff they did not have license to download in the first place) still infringed copyright just like anybody else. Effectively the courts have been holding that if you study material you have license to access, you aren’t infringing, but if you pirate that material, even if it is merely to study it, it’s still infringing. For better or worse this is basically basically how it’s always been.
I have no idea what Trump is proposing. Like most republicans, but especially him, he is incapable of even approaching understanding of nuanced and technical areas of law and/or technology.
Richard Stallman, the creator of the GPL, a “copyleft” license. The problem is that Open Source Software is entirely reliant on a strong copyright system to be enforced. There is nothing else that prevents companies from just keeping everything proprietary, even if it’s all oss under the hood.