Without knowing the details of what you're talking about, I'd say on first principles the owner(s) of an instance has the final say on what posts they allow on their platform because it's their platform, they don't owe you anything. The benefit of the fediverse is that anyone can have their own platform so if you don't like one platform you can post elsewhere. Just as it was with forums before the tyranny of centralised social media. So I'd be inherently more sympathetic to a mod removing a post than someone insulting a mod but it may vary depending on details, such as if the mod was doing a bad job for their platform.