Well, I got my first white supremacist reply from the fediverse after posting an article about Elon from Flipboard.
I reported and blocked the account. I also looked at the instance admin's account and it's clear he's also a white supremacist. So that instance will be blocked on flipboard.com and flipboard.social as well as shared with other instance admins as a problematic instance for them to take action if they also deem appropriate. Took all of 2 minutes to help make the fediverse a bit better for everyone.
And the best thing is that anyone in the fediverse can do this too. Decentralized moderation FTW.