It's obviously impossible to know that, so instead of nitpicking, let's graciously interpret it as acknowledging that he (et al) did contribute a great deal to the foundations of free software we have today.

I'm not claiming this to be a priori knowledge; that's how causality works, I don't know that Barack Obama was elected because I chose not to eat a cheeseburger in 1999. RMS laid the foundations for the free software movement, growing the open culture and creating a good licence. I think it's hard to debate that what RMS has done hasn't improved the free software landscape today.