> What's better for society doesn't matter in the face of the Constitution which is what the SCOTUS will judge this on.
The Constitution only says
> The Congress shall have Power [...] to promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries.
most of copyright is defined in statute (the various copyright acts) and court precedent.
Yeah, the Copyright Clause is pretty unusual. More than literally anything else in the Constitution, copyrights and patents actually are supposed to be judged in light of what's better for society.
Most stuff in the Constitution gives the government the power to do X (sometimes stating explicitly that it's for reason Y). The structure of the copyright clause is that Congress has the power to do Y, using mechanism X — a strict reading of that means that the government cannot do X for reasons other than Y, and cannot pursue Y using means other than X, and definitely shouldn't do X for reasons of not-Y.
I have a hard time believing SCOTUS will toss 50 years of standard practice in the software industry in the trash bin, regardless of what the law says.
Every programming language has stolen large portions of their API from other languages. Even Java.
As an example, the Z80 and the 8080 were interoperable and it was better for everyone.