Simon Janes
gab.ai tells me nothing of where they're incorporated and how exactly they're going to guarantee no censorship; that usually is a challenge for the Internet to overcome.
Mark Dain
Reading the terms of service and community guidelines, I'd guess USA. They follow DMCA and ban terrorism (as defined by the US government). As for garaunteeing, well that's more tricky. The fact you have to login to see anyone's posts is possibly one way to do this. It's harder to argue the site should take some content down when it's behind a login.