No, it doesn't, at least in any way relevant to the immediate discussion.
> It's also illogical to single out a movement for being small, given that every movement starts small, and most movements fail.
It might be, but no one is doing that. What is being argued is that examination of the success of particular movements distinct from other movements that also start out small shows the ways in which movements which start out small can manage to avoid the usual result of failure. What they are being singled out for is distinctions like (in the upthread post) clear goals, strident and unrelenting leadership, etc.
One can argue about whether or not there is sufficient evidence that these traits are the right ones on which to pin their eventual success, but nothing about the argument rests on singling out a movement for being small.
Also note how vocal minorities with clear goals achieved in the past some serious shifts in mass consciousness. Black rights, women rights, gay rights — these things were not lead by establishment, or even by excessively huge groups. These were lead by vocal, unrelenting activists, initially seen as idealists and nuts. Exactly like RMS looked 20 years ago, and Snowden looks now.
First, the idea that civil rights is a movement originally led by "lead by vocal, unrelenting activists, initially seen as idealists and nuts" assumes facts not in evidence. In fact, a huge portion of the US population sympathized with civil rights and the vocal leaders of that movement even before the civil war: civil rights supporters weren't even seen as nuts when Africans were still chattel slaves in the south!
Second, I'm sure there are successful movements led "by vocal, unrelenting activists, initially seen as idealists and nuts." But that also describes the Michigan Militia, the antivax movement, and Branch Davidians.
My argument is simply that we cannot assume anything about the legitimacy of a movement by the outsider status of its early adherents. The onus is on you to show that we can.
For example, the idea that black people should be the legal equals of white people was indeed seen as nuts by most Americans before, during, and even following the Civil War. There existed a huge gulf, even among abolitionists, between the idea that black people should not be property, and the idea that black people are entirely equal. The movie "Lincoln" touches on this a bit--even while arguing in favor of the 13th Amendment, every political leader agreed publicly that black people could never be equal with white people.
That gulf has essentially collapsed now, so it's hard to appreciate how large it actually was. And it collapsed progressively. First, people weren't property any more. Then they were citizens and deserved equal treatment under the law. But then it took 100 more years before Americans broadly agreed that federal law should protect their right to sit where they wanted on a public bus.
Likewise in the gay rights movement, which saw its first public airing in establishment settings at the beginning of the AIDS crisis. There weren't reporters asking President Reagan (or any previous president) about gay rights, but they did start asking questions about AIDS, which at the time was thought to only affect gay people. But if you go back and read the transcripts, not only did the Reagan press secretary publicly mock being gay, the reporters played along with the jokes, even while asking pointed questions about AIDS. Being gay had such low social currency, even among liberals, that it took a massive public health crisis to even elevate it into broad public conversation.
I agree with you that the mere fact that a movement starts "outside the mainstream" does not help predict that it will succeed. But let's not forget to take off modern glasses when looking at the cultural environments in which the movements we know today as successful, started.