Lewis talks about the ways in which Twitter has raised his profile and publicized his work. That’s the good thing about a public medium! But when you say things in public, some times mean people say mean things about what you’ve said in public. That’s the bad thing about a public medium! There are options you have to get the publicity; there are options you have to avoid the meanies. There are no options that give you both. Lewis completely undoes his own point when he mentions having a private, invite-only Twitter feed. Don’t like mean people? There you go, Matt: make your tweets private. But he wants both, the publicity and the protection, and you can’t have that.
Lewis’s problem is not with Twitter. It’s with that basic contradiction.