Yes, so he cares about the freedom of the user to change software. He doesn't care whether or not these users share these changes with each other and collaborat

Yes, so he cares about the freedom of the user to change software. He doesn't care whether or not these users share these changes with each other and collaborate to develop the software. Although he thinks that's a nice-to-have side effect. He cares that this freedom propagates to all users, not just you, and so just like he gave you this freedom, you also must pass on this freedom.