@mhunter saying you are leaving mastodon is kind of like saying you are leaving email. There are over a thousand mastodon servers and each one is independently owned and operated by different people, and some of them are indeed alt-righters.
As a result, unlike Twitter there are many more ways to avoid such trolls. You can find a server with stricter filtering or federating policies where trolls are filtered like email servers filter spam, if that suits you more.