> Stallman has called for the killing of babies with Down Syndrome.
I've been in OSS for decades. I've actually argued with RMS personally on certain subject (he called me evil, which I disagree with, but that's not the point). I've read a lot of his writings and a lot of writings about him. I never heard about this until today. I have no idea what RMS actually said on the subject (you didn't provide a quote, as it usually happens) but whatever he said, it's clearly wasn't something very important among all his body of work, if mostly nobody heard or cared about this so far.
In fact, I can't bring myself to care about RMS's views on the subject right now - even if your most uncharitable interpretation is completely correct (I am 99% sure it's not, but even in unlikely case it is) it's completely immaterial. RMS has never been and never will be in a position that such an opinion would matter for anything, he has never killed any babies and has never contributed or influenced anything that mattered in this area. He did, however, contributed a lot and mattered a lot in other areas.
One of the most idiotic and toxic features of cancel culture is reducing the immense complexity of the person's life to one - almost always distorted and misinterpreted - statement and focusing on it as if it were the only point ever. There's no "someone like that". "Someone like that" is a bullshit - no one is "like that", and "like that" is an insanely awful criteria to guide your actions. Literally everybody has done something in their life some people may not like. One can disagree with somebody on some subject and still agree with them on other subjects. That's how human society works. People can not be reduced to a single "like that", and shouldn't be. Get out of Twitter and purge it out of your system, for the benefit of yourself and humanity.