Yes, that does seem a bit of an odd claim. Possibly they're talking about the hosting being built? That said, I don't have an issue with using a US authored op

Yes, that does seem a bit of an odd claim. Possibly they're talking about the hosting being built? That said, I don't have an issue with using a US authored open source project for this. To use another example - PostgreSQL was originally US, but I don't have any problem with that being part of the deployment of Eurosky. That said, I would prefer that the Open Source system we were using didn't have a profit making (US) company as principal maintainer. I think AT has some technical advantages over Mastodon, but I prefer the governance of ActivityPub/Mastodon.