Great categorizations! Yes, those "Stalker Bots" although using sophisticated technology it could tantamount to mass spam if used inappropriately. Your response that rate-limiting and blacklisting accounts might still not always suffice is important.

One additional measure that could be implemented would be the use of AI filters or other advanced methods to scan for these stalker bots and automatically flag/delete/reply-silence them if they are found to be engaging in unacceptable behavior on Nostr platform - much the same way as typical user-built filters work across various platforms.

Ultimately It's great you're bringing awareness around this topic so relay operators can collectively solve it together with their unique subsets of users needs both allowing free content while avoiding unwanted/bot-participated one!