Give it enough time and every instance is going to defederate with everything that has even slightly opposing view points. We will have federated islands because people would rather silence opposing thought than discuss something like a reasonable human being.
If you want to discuss healthcare, taxes, etc, I'm all for it, but if you want to discuss stripping rights away from people or harming them, or you can't have a conversation without using dog whistles or coded language, then we have nothing to discuss.
The issue with this mentality is that creates a viscous cycle that leads to extremism. When you close yourself off to ideas, you rob yourself the exposure to different perspectives and criticism. You will only hear what you want to hear, aka an echo chamber. The issue with echo chambers is that the lack of intellectual diversity and criticism allows more extreme views to take hold. For example, it's easy for an echo chamber to justify imprisoning people they don't like because everyone thinks the same and there's nobody to challenge the bad ideas. Free speech can't be used and applied selectively. It has to be universal and it has be genuinely free. Extreme ideas will get criticized, moderate and pragmatic ideas will rise. There's a reason why genuine democracies tend be tame politically and against extremism. Your mentality lets radicals stay radical while at the same time turning yourself into one. You have to hear different ideas, views, and perspectives even if you disagree, get offended, or think they're vile. Hate, authoritarianism, and ignorance can't be defeated with more hate, authoritarianism, and ignorance.
I can tolerate a lot but I won't tolerate intolerance. If your side is intolerance, bigotry, hatred, and hurting people, then yeah I'll defederate my instance pretty damn quick.