Stallman doesn't actually oppose anything that you said. He actually said Steam is a net positive for GNU/Linux adoption, even though he doesn't like it.
The libre software philosophy doesn't equal isolationism so saying that it's irrelevant is completely missing its point. Standing for software freedom is standing for the user empowerment, remix culture and privacy, the Open Source movement is a non-movement, it only cares about development, not privacy or user freedom, those things are completely secondary to them, same with the copyfree advocates (the two things are pretty much synonymous in my eyes, it's just semantics). Emphasizing the four freedoms is enough to be considered a software freedom activist in my view, you don't need to be a hermit. Neither Mako nor Snowden are and yet they are the more outspoken FSF allies.