You actually don't need to campaign to defederate every instance that offends you. Lemmy provides the ability to report posts and block posts, users, and instances. I get that there are a lot of shitheads, assholes, and idiots on the Internet... Defederating might be throwing the baby out with the bathwater in many cases. Hell, if you listened to everyone shouting about the assholes you shouldn't support no one would be on Lemmy at all. Also, small I hobby instances are run by people with lives. Perhaps the admin will have time in the near future to clean up what's been reported. Or maybe it really is abandoned. We just don't know.
When someone starts campaigning to defederate an instance it immediately starts my senses tingling because I think I'm getting a version of the story... and it's doubtful I'll hear the other side. It offends the same part of as people complaining about downvotes did on Reddit. Take advice from a cartoon dog. "It's not the done thing." Or it shouldn't be, at least.
Had this post just been letting people know what you observed about the instance I would be more moved to investigate and perhaps report posts and block the instance. I might still if I see hateful speech in All... but the implication that their hate will fester, breed, and spread if they aren't immediately defederated is using the same tactics that right wing populists are... by dehumanizing people and playing on other people's fear. It is just as wrong for you as it is for them to do it.
Look at your school's policy manual. There's likely a policy regarding what they can and cannot do with images of students. Every school I've worked for has some kind of policy around this. In all of them I've read you can opt out of photos being published, but there's usually a caveat that by participating in any school sanctioned event, participation is considered consent to be shown in photos and video of the event.