I don't think the fine is automatic like that, it's more if you don't have an appropriate mechanism to manage it. In other words you need a content policy that is enforced.

A mod who deletes nude pictures is probably enough to not get fined.

I think the real issue is what I just said... "probably enough"; that's the real problem with the online safety act. People are mostly illiterate on the law, and now asking them to understand a complex law and implement it (even when the actual implementation is not that much effort or any effort at all for well run spaces) is the real issue.