Honestly, this drama every time an instance decides to defedarate needs to end. Freedom of association exists. If someone decides the don't want to be around you for whatever reason that's their right.
I just went to blahaj to check their post on this and the majority of people there seem okay with this decision, and those who aren't are free to go to a different instance.
One good thing about lemmy is that an instance defederating from yours doesn't affect you in any way. Your content isn't being taken down and can still be viewed by those who want it.
Isn't this the whole point of the fediverse? Freedom to choose by yourself what content you want instead of having a central authority decide for you and being stuck with that choice?
Yet every time something like this happens there's drama. It's absurd.
From what I read there it sounds like the admin is not okay with the idea behind the sub even if it didn't turn out to be child porn. So, it started as a misunderstanding, but the reason to defederate is different opinions about what content is acceptable.