Trello is based in NYC. I don’t know the actual corporate structure, but they could potentially be spun into a controlled company, maybe, to avoid this law somehow.

To be honest, Trello is the least of your worries, with Atlassian. Authorities having unfettered access to all your code, regardless of privacy settings, is more worrying imho. Then again, GitHub is US-based and the PATRIOT Act already gives that power to US authorities, so if you care about that, self-hosting in the only way.