I say this not to explain to you, but to clarify a common misperception that it’s somehow the “real” Mastodon. It’s not, in exactly the same way that Gmail is not the “real” email.
Sure, an account could be made on a other instance, but that doesn’t change the mindset behind how the instance run by the maintainers is handled, which we can only assume will influence the project as a whole.
Also, moderation policies vary wildly. The instance I run moderates much differently than mastodon.social, which tends to get a lot of criticism for being seen as chronically under-moderated, if anything.
I think at least one of their moderators was insulted by that personally.
Free speech has never meant that you can say whatever you want anywhere you want with zero repercussions.
Provided the person isn’t breaking any laws by saying what they’re saying, leave the post up and they can get their repercussions, positive or negative, based on their post being available.
I know people like to take a hard line view and say a violation of free speech is only happening if the government is arresting you for what you say, but in my opinion it’s everyone’s responsibility. To have the privilege of free speech means one must also be tolerant to hearing things they don’t like from time to time. After all, free speech doesn't exist to protect popular opinion, it exists to protect the unpopular.