When I was a student, I took many surveys conducted on Mechanical Turk by any number of Ivy League universities. So in regards to your methodological objections, the one against conducting such surveys in that venue doesn't seem well founded.
And yes, a completely unscientific facebook article, whose purpose is obviously merely to reinforce a narrative that the author's have already decided is true, is hardly worth debunking. Is this guy's "study" slightly more accurate than that? Well yes...but so what.