"I'm no expert in EU law, and so I'm likely wrong here, but it may very well
be illegal."
Thanks to things like the Berne Convention, copyright is recognized in almost
every country of the world. And so the distribution of a program without the
permission of the copyright holder (the company in this case) would mostly
certainly run afoul of copyright law, creating problems for the people doing
the sharing (even if they didn't work for the company.)
And of course copyright applies here - the GPL relies on it in order to have
teeth (i.e., your rights terminated if you don't comply with the license and
so if you're still distributing after the license has terminated it's
basically just your normal case of copyright infringement because the person
is distributing copyrighted stuff without permission (no license - because it
terminated.)
It seems the better question might be: How to work on getting the company to
release its software as free software? Then all of these issues are gone.
Because what the original poster is proposing in this thread (leaking the
source code of proprietary programs) would not be free software. Free
software is about being able to *legally* modify and share things (copyright
governs both modifying and sharing, which is why the GPL works.)
So why does this thread even exist? Hoping for software to be leaked that
we'd never be able to legally modify and share anyway? I don't want to go to
jail for sharing things. That's why I use free software: So I can legally
share with my friends, and not have to feel bad for doing it.