Actually, the behaviour of the Mastodon author promising a "safe space" in his paid, targeted advertising campaigns without any real plan for data security is the unethical behaviour. If you don't like that people can scrape the fediverse, fix the damn security.
What behavior is that? Writing a tool that people can use to download information published on websites? Does the creator of `wget` or `curl` put people's lives at risk too? Chrome?
I think perhaps you may have misattributed the responsibility for the side effects of publishing data globally.