Almost like he is a person that thinks about principles and morals a lot and doesn't have a position that can accurately be summarised with a ready made label...
[edit] if you follow any of RMS's thinking he is generally quite precise and careful in his writing, choosing words carefully, eschewing ready made labels and coining his own with more precise definitions.
So it would not surprise that referring to Stallman as say a "lefty", "communist", "libertarian" or a whatever would annoy him, since there is no good consensus on what those terms actually mean.
I would posit that the use of over-broad popularly contentious labels is generally counter-productive to actual thinking and one of the major problems in modern political discourse - it promotes tribalism over thinking about issues.
So what does "freedom" mean, he uses so much? Is there a clear consensus on that?
I believe allmost everyone says he or she is for "freedom".
Slavers and Nazis used the term freedom as well as the actual slaves, workers, whatever.
So yeah, he also defined his version of "freedom", but labelling sounds very RMS to me. Also the strict wording of "ethical" software, meaning only the licence he favors is ethical and good and everything else, not.
A good place to start would be this essay: https://www.gnu.org/philosophy/free-sw.en.html - which he wrote because the term "free software" (as you correctly observe) would be too fuzzy.
RMS has his faults but ambiguity is not one of them. He really bends over backwards to be careful about explaining what he means.
[edit] if you follow any of RMS's thinking he is generally quite precise and careful in his writing, choosing words carefully, eschewing ready made labels and coining his own with more precise definitions.
So it would not surprise that referring to Stallman as say a "lefty", "communist", "libertarian" or a whatever would annoy him, since there is no good consensus on what those terms actually mean.
I would posit that the use of over-broad popularly contentious labels is generally counter-productive to actual thinking and one of the major problems in modern political discourse - it promotes tribalism over thinking about issues.
Labelling is a poor substitute for reasoning.