I hold a Ph.D. in an applied area of psychology, and I think Rush is a bit too soft on a couple of subjects; so be careful of painting with too broad of a brush.
I was a student member of the APA while I was in grad school and got so disgusted with them that I quit. When I told my research director, he was amazed and said he had been trying to work up the nerve to do the same as he was sick of the leftward tilt of the group. He finally did.
So you’re one of the article’s three. Three out of a thousand is close enough for the author, and me, to say “all” in casual commentary or conversation. Don’t be an over-literalist. Please don’t be picayune. My wife is an occasional literalist; a close coworker is is a hyper-literalist. I often want to (not literally) kill them for it.