IMO, this is how we get echo chambers. I understand wanting a safe space, but that should be something community moderation should provide, not instance-level defederation.
To be clear, I disagree with the MAGA movement on pretty much everything. I used to consider myself Republican back when I thought Republicans actually want smaller, fiscally responsible government, and I didn't join the Dems because they never seemed to prioritize civil liberties (e.g. gay marriage became legal by court decision, not statute, much like Roe V Wade).
I left largely due to conversations and content online (mix of Reddit and YouTube), and that wouldn't be possible if popular social media sites cut out chunks of the conversion. In fact, I very much disagree with the aggressive stance YouTube took WRT COVID misinformation, not because I think misinformation is acceptable, but because it shut out anyone who was critical of the government's policies. I want to live in a society that values differences in opinion and is okay with that being uncomfortable.
There's a balance to be struck here, and I think that balance point is whether we can work with the admins of an instance to remove problematic content and users. I haven't seen anyone saying that's an issue, the arguments all revolve around the domain name and sometimes posts in communities that are obviously biased.
We defederate Hexbear not because they're tankies, but because their admins refused to take action against trolling. IMO, that should be the standard.