I don't think this is true, popular tweeters, including Elon, often spread misinformation that functions as right-wing propaganda. Typically they just quote tweet someone else, add on nothing like "interesting..." or "wow..." and then post it. Of course, they're quote tweeting actual far-right pundits or sometimes neo-nazis. There're some arguments about plausible deniability - I don't know if someone like Elon is aware that some of the people he's quote tweeted are neo-nazis.