That's true, but the GPL is just a neat tool that Stallman invented to work within the current legislation, it's not an actual component of his philosophy. For example, he supported a change to the laws that would shorten the GPL, as long as it also forced proprietary software to open up after a while[1]. He also specifically said that copyright is "no longer beneficial" and proposed major reforms, including eliminating any restrictions on private sharing of works[2].

Stallman's philosophy is that all software should be Free because the users deserve it, not because the author wishes it to be.

[1] https://www.gnu.org/philosophy/pirate-party.en.html

[2] https://www.gnu.org/philosophy/copyright-versus-community.en...