But that's not how copyright works here, so this analysis seems irrelevant.
> 1. The derived work is transformative. It uses the original as inspiration but the end result is substantially different.
It's not. Changing variable names isn't a substantial difference.
> 2. Only a trivial amount of the work is copied (a few lines of code out of thousands/millions).
That doesn't matter. Relative size doesn't matter, absolute size does.
> 3. It is hard to prove that the creators of the original work were damaged by copilot (for example did they lose any customers or revenue?) This is normally the single biggest test in such cases.
??? No? You appear to have no clue how copyright works or what copyright infringement does. It's damaging solely in that you don't have the right to reproduce it without my permission. It's mine.