I don't consider being on Threads as being "on the fediverse". My definition of the fediverse is servers that follow the Activity Pub protocol to interact with each other. You might disagree with that definition, but Threads only lets us "follow" (view-only) certain of their accounts (only about 2000 out of millions) from Mastodon. Those accounts do not see any replies to their post from the fediverse, or any fediverse posts at all for that matter--we are invisible to them. So no, he's not "on the fediverse", he's on Threads. I doubt he knows the fediverse even exists.