Stallman has been pretty clear on the political nature from early on. What gives you the impression that free software hasn't been political? Perhaps there's a difference in definition of free software.
With GNU, and the Free Software Movement, the Free is definitely free as in freedom, which is a political concept.
A program is free software if the program's users have the four essential freedoms:
The freedom to run the program as you wish, for any purpose (freedom 0).
The freedom to study how the program works, and change it so it does your computing as you wish (freedom 1). Access to the source code is a precondition for this.
The freedom to redistribute copies so you can help your neighbor (freedom 2).
The freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.
A program is free software if it gives users adequately all of these freedoms. Otherwise, it is nonfree. While we can distinguish various nonfree distribution schemes in terms of how far they fall short of being free, we consider them all equally unethical.
Richard Stallman, the founder of the project, views GNU as a "technical means to a social end". Relatedly Lawrence Lessig states in his introduction to the 2nd edition of Stallman's book Free Software, Free Society that in it Stallman has written about "the social aspects of software and how Free Software can create community and social justice."
