Don't want to hijack the thread too much, but I don't really understand how you can fix *people* with technology.
I will be glad when Twitter will make the algorithm open source, encrypt the DMs, make tweets editable, maybe even add some characters... But I don't really think this will change much the state of our democracy (well, maybe a bit the algo part, but he should also look at Facebook and Youtube, and above all, their business model).
A friend of mine - who was a designer for the Wikipedia software - once wrote that you always have to "design for evil", meaning that your tools and your platform will definitely be used buy some crazy people with a lot of stamina and a lot of time. He was simply thinking about online trolls, but you have hostile nations hacker teams, spambots, ecc.
You won't fix democracy with Twitter: I think there's a more than fair chance he will improve some Twitter bugs, but I'm quite skeptical about the whole free speech thing, at the moment it seems just the far right is happy about this.
Now, I live in Europe, where we don't have the First Amendment and are far less enamored about "Free Speech" as an absolute than Americans. We had Nazism and Fascism here, probably that's the reason.
Bad actions are always preceded by bad words and bad arguments (the viceversa is not true, but still).