That looks to have some pretty radical politics at its core. No thanks.
What is it you were looking to partake in? Racism, violence, fascism, colonialism, white supremacy, religious extremism, nationalism, homophobia, or transphobia?
You can join any other Mastodon server, and still follow him even though you're on a different server. Just put his handle (the one you can find on his site) on the search bar of your Mastodon server after logging in.
Choose another. They don't all have to be on one email server, and they don't all have to be on one Mastodon server.