>> The GPL is a legal tactic of the FSF movement, who believe that intellectual property in software is immoral

> This is not correct.

Well, it is basically correct. The core idea of the Free Software movement is that all software should be free. They believe that software not fitting their subjective definition of "free" is immoral (or evil).

This has been declared quite a few times by Richard Stallman; for example, here:

“The free software movement aims for a social change: to make all software free so that all software users are free […]. Every non-free program gives its developer unjust power over the users. Our goal is to put an end to that injustice.” -- http://www.gnu.org/philosophy/compromise.html

I admit, the word "intellectual property" was an unlucky choice by the previous poster.