You can’t possibly have a legal copy of the software without expressed permission of the author. They may not care who does what with it (IDK, implied permission?) but they could change their mind at any time and chose to enforce their copyright. Which also means first-sale doctrine doesn’t apply as there was no “first sale”.

I also “make copies for my own use” of TV shows, written things, &etc and don’t think anyone would claim that isn’t violating copyright law, especially the producers of said content. In fact, I know this to be true as they have sent me nastygrams via email before. Also, by your reasoning, any company, like a cloud service, could take any code they want as long as they weren’t committing acts of distribution and use it however they want. I think we all know this isn’t the way it works because the anti-cloud licenses which have become popular lately would mean absolutely nothing.

And fair use is not really applicable to the current discussion because statically linking a library without permission isn’t fair use.